the risk of climate change to britain's biggest roman structure, a warning artefacts preserved for centuries near hadrian's wall may soon rot away. hello and welcome. the nato secretary general, jens stoltenberg, has warned russia that any further aggression against ukraine would have severe costs. he spoke after talks between the us and key european leaders over a common strategy towards moscow, which denies planning to invade its neighbour. the us has placed more than 8,000 soldiers on a heightened state of alert, to bolser nato�*s presence in eastern europe if needed. moscow denies planning to invade ukraine despite more than a 100,000 troops close to the ukrainian border. 0ur correspondent gabriel gatehouse sent this report from the ukranian capital kyiv. bell tolls this is a country in limbo, waiting for an invasion that looks more likely with every passing day, but may yet never come. to the east, 100,000 russian troops are massed, but the kremlin says talk of an invasion is hysteria. facing them are ukrainian soldiers who hear western leaders sounding the alarm in ever starker tones. and stuck in between are the people of kyiv who, frankly, don't know what to believe. i think something might happen. i think the probability is very high, but god knows. i think even putin doesn't know yet what kind of decision he's going to take, so... but the situation is horrible. at the weekend, britain warned that russia was planning a coup to install a little—known, former mp as puppet ruler, suggestions that have been widely dismissed both in moscow and here in kyiv. the uk began pulling staff out of its embassy today, saying an invasion could come at any time. the americans are doing the same. a senior ukrainian politician told the bbc today such actions are not helpful. translation: if people start panicking, - that leaves our country in a very dangerous position. and it will make it easier for russia to manipulate us. the reality is, of course, that this country is already at war and has been since 2014, when russia annexed crimea and funded and provided weapons and sent in troops to support a separatist rebellion in the east. around 111,000 ukrainians have already died in that conflict. these are some of their faces. and so for people here, the question is not, "will there be war?" but "will this war escalate?" for months now, the ukrainians have been preparing a territorial defence force. volunteers like marta yuzkiv, a doctor in her 50s, is among those who are training for a possible defence of kyiv. of course i am worried. because i'm a peaceful woman, i don't want to have a war started, but in any case, in case it starts, i should be ready to defend the country. meanwhile, a kind of normal life continues as the people of this country wait nervously to see what fate and larger geopolitical forces have in store. gabriel gatehouse, bbc news, kyiv. 0ur north america correspondent david willis has been assessing the details of the biden administration plans to place more than 8,000 troops on standby to reinforce nato�*s eastern flank if needed. the us has placed 8500 troops on a state of heightened alert for possible deployment to eastern europe in the event that nato needs help. they include surveillance and reconnaissance trips that are expected to join the 40,000 strong nato emergency response unit. the move represents a pivot on the part of the biden administration which up to now had been restrained as far as its response to the crisis along ukraine's order was concerned, for fear of concerned, forfear of antagonising russia. concerned, for fear of antagonising russia. the concerned, forfear of antagonising russia. the biden administration has stepped up its weapons shipments to kyiv but it continues to insist that it has no plans to send us troops to ukraine to fight against russian forces and that this is all part, this 8500 troop commitment is all part of establishing and reinforcing the united states response to and support for nato. even though as it continues to seek a appomattox solution, the united states and some of its western allies are taking the kind of steps that very often lead to some sort of military engagement. daniel treisman is a russian expert and professor of political science at ucla, hejoins us from los angeles. welcome to the programme. so from your perspective, of course at the moment everything seems to be ratcheting up and heading towards conflict. what needs to happen now to prevent that from going ahead? 1 needs to happen now to prevent that from going ahead?- that from going ahead? i have to say we _ that from going ahead? i have to say we don't _ that from going ahead? i have to say we don't know - that from going ahead? i have to say we don't know for - that from going ahead? i have to say we don't know for sure | to say we don't know for sure that the russians are actually planning to invade, it is certainly possible, they don't have enough troops there yet, they would need may be up to 200,000 but it certainly seems to be looking in that direction in a very worrying way of stopping what needs to happen is that diplomacy needs to continue along with an increase in the defences as we have seen with president biden putting these troops on alert, sending weapons to many other countries, defensive weapons to kyiv and continuing to insist on how severe the sanctions will be if anything like an invasion actually occurs. in invasion actually occurs. in terms of — invasion actually occurs. in terms of diplomacy, you say of course it is so vital that the diplomatic route is pursued as much as possible. where can ground be given?— much as possible. where can ground be given? well, we can't cive ground be given? well, we can't give ground _ ground be given? well, we can't give ground on _ ground be given? well, we can't give ground on the _ ground be given? well, we can't give ground on the basic - give ground on the basic demands that putin has made. he has made is very maximalist demands which would involve really withdrawing nato to it 1997 borders. he wants all nato troops and weapons to be withdrawn from the new nato country since then. what perhaps could be discussed are things like the revival of the intermediate range nuclear forces treaty which broke down some years ago, we can talk about other aspects of nuclear security, have agreements on having fewer military exercises near the borders of russia on both sides, and various other things could be negotiated. the problem is all of those things could have been pursued without this massive buildup of military force on ukraine's order so it seems unlikely that those things would be enough to satisfy putin at this point. without the pressure though that has been put on both sides in recent days, do you think that any sort of diplomatic solution would have been pursued?— solution would have been ursued? ~ ~ ., , , pursued? well i think obviously we are in a _ pursued? well i think obviously we are in a situation _ pursued? well i think obviously we are in a situation that - pursued? well i think obviously we are in a situation that has i we are in a situation that has been created by the pressure that putin has been applying to ukraine. this massive buildup of troops, these various signals that he has been sending, this leaking of worrying stories about plans and the supposedly potential coup in kyiv, so the force that has already been demonstrated created this crisis, clearly the russian side hopes to extract some concessions and return for simply withdrawing the troops and that is the situation we are in. we have to maintain a very tough and united front, resisting that kind of pressure because if you give that once, it won't be the last time, this will occur probably quite quickly. {eek probably quite quickly. 0k daniel, thank you for your analysis on this. and just to say and our business coverage in about 20 minutes time we will be looking at the applications for the energy markets, gas prices spiked on monday on the news that uk us embassy staff were being advised to leave ukraine, if there is a conflict in the region what could it mean for european gas prices? all of that to be discussed later. borisjohnson is facing renewed anger following yet another revelation about gatherings within government during lockdown. downing street has admitted that number ten staff met briefly in the cabinet room injune 2020 — where they were served cake to celebrate the prime minister's birthday. the rules at the time banned most indoor gatherings of more than two people. 0ur political correspondent, chris mason, reports: the parameter has long said that my policy on cake is pro— having it and pro eating at. so much so that he had two on his birthday stopping the first at school and hertfordshire he visited in the morning. and another when he got back here to the cabinet room in downing street, the very spot where the covid rules were signed off. his now wife carrie brought another cake along for a gathering of up to 30 people at around two o'clock which lasted at around half—an—hour. there were sandwiches and picnic food and no discussion about social distancing. but and no discussion about social distancing-— distancing. but his supporters sa i distancing. but his supporters say... ithink— distancing. but his supporters say... i think some _ distancing. but his supporters say. .. i think some of- distancing. but his supporters say... i think some of these i say... i think some of these allegations have got a little bit out of hand stopping what really happened here is a group of staff, small group of staff who had been working closely with the pro— minister brought in a birthday cake at the end of the day and there was ten minutes there around sharing a piece of cake. i don't think that really constitutes a party in the way that some of the other more serious allegations that are being investigated may be due. it’s that are being investigated may be due. �* , , that are being investigated may be due. 2, ., ., be due. it's yet another get-together _ be due. it's yet another get-together to - be due. it's yet another get-together to add - be due. it's yet another get-together to add to | be due. it's yet another i get-together to add to the be due. it's yet another - get-together to add to the list get—together to add to the list of dos around westminster we already knew about, and there were more than a few. those conservatives who want boris johnson out think this could persuade more to reach the same conclusion. persuade more to reach the same conclusion-— conclusion. no-one has ever misunderstood _ conclusion. no-one has ever misunderstood the - conclusion. no-one has ever misunderstood the job - misunderstood the job description of party leader more than borisjohnson. this could be the straw that breaks the camel's back. an could be the straw that breaks the camel's back. an allegation of islamophobia, _ the camel's back. an allegation of islamophobia, the _ of islamophobia, the resignation of a sitting minister at the dispatch box in the lord, and then another revelation about what went on here earlier in the pandemic. and it's only tuesday. let's get some of the day's other news. in germany, a gunman has killed one person and seriously injured three others inside a lecture hall at heidelberg university in the south—west of the country. the police chief in charge of the investigation said the attacker, who was armed with two guns, later killed himself. he was an 18—year—old german. a rare snowstorm has blanketed swathes of the mediterranean, causing blackouts, traffic havoc and closures. europe's busiest airport has shut down in in istanbul, after the roof of a cargo terminal collapsed under heavy snow. schools and vaccine centres have closed in athens, and hundreds of drivers have been trapped in their cars. the james webb space telescope, one of the most powerful instruments for studying the cosmos, has arrived at its final destination, around a million miles from earth. the highly sensitive, heat shielded telescope will now be made ready to observe the universe's earliest stars, in a process that will take five months. at least eight people have been killed in a stampede outside a football stadium in cameroon ahead of the host team's, africa cup of nations match against comoros. the crush happened when fans tried to join those inside, by rushing through the stadium gates. the confederation of african football, which organises the tournament, says it is investigating the situation and trying to get more details about what had happened. in the game itself, which was watched by thousands of fans outside as well as inside the ground, cameroon progressed to the quarter—finals beating comoros 2—1. our sports reporter piers edwards was commentating on the game so was inside the stadium, but gave us this update. a 14—year—old was among the eight victims who died in a crush outside yaounde's 0lembe stadium ahead of cameroon's crunch africa cup of nations clash with comoros. the incident occurred as fans tried to force their way in roughly half—an—hour before kick—off. the incident took place at a perimeter gate where spectators were pushed against the fences by the sheer number of those trying to get in. shoes and clothing were amongst the debris that littered the site. some 50 wounded have been taken to a nearby hospital where there were harrowing scenes of those mourning their loved ones. a nurse there has told reporters that some of the wounded will need to be taken to more specialised hospitals. cameroon, which is hosting africa's greatest sporting event for the first time in half a century, has been beset by organisational problems in its staging of these finals. they should have first been played in 2019 only for late preparations to cause the delay. african football's ruling body, caf, has sent a delegation to visit victims in hospital. now, games here should have a limit and a maximum capacity of 80% for matches involving the host nation, cameroon, but there appeared to be more than that number inside the 0lembe stadium during a victory which was ultimately overshadowed by tragedy. piers edwards, bbc news, 0lembe stadium, yaounde. stay with us on bbc news, still to come: a wandering wallaby who escaped from a farm in eastern england's finally captured, almost three weeks and a few failed attempts later. the shuttle challenger exploded soon after lift—off. there were seven astronauts on board, one of them a woman schoolteacher. all of them are believed to have been killed. by the evening, tahrir square, the heart of official cairo, was in the hands of the demonstrators. they were using the word 'revolution'. the earthquake - singled out buildings and brought them down in seconds. _ tonight, the search for any survivors. has an increasing desperation about it as the hours pass. i the new government is firmly in control of the entire republic of uganda. survivors of the auschwitz concentration camp have been commemorating the 40th anniversary of their liberation. they toured the huts, gas chambers and crematoria and relived their horrifying experiences. this is bbc news, the latest headlines: the us puts thousands of troops on standby for deployment, as russia's military activity continues near ukraine's border. another party hangover for borisjohnson , downing street admits holding birthday events for the pm during lockdown. stretching 73 miles from coast to coast, hadrian's wall, which sits on the border between england and scotland, gives us an invaluable window to another time. and throughout this year, numerous events are being held to mark 1,900 years since its construction. but there are concerns that climate change could be erasing our past on this ancient site. justin rowlatt is there. for the romans, this was the end of civilisation. at 73 miles long, hadrian's wall is the greatest roman structure in britain. it's reckoned it took 15,000 men six years to build, and the sites around the world have been a source of some of the most incredible roman artefacts ever found in britain. the waterlogged peat soils here mean organic materials like this child's sure don't rot. they found boxing gloves, some of the oldest handwritten messages in the world, even a roman toilet seat. but now climate change is threatening the ancient objects preserved along the wall. 50 preserved along the wall. so what preserved along the wall. sr what we've got here is a field where it should be very, very wet, what is happening is that it is drying out, and the land is dropping. this is magna, one of the biggest roman forts the site has never been dark and archaeologists are now worried because the treasures buried here could again to rot away. pretty much everything that they used on this site, for 300 400 years, has been potentially preserved in more or less the same state it was thrown away in, under the ground where we are standing. which is an incredible opportunity. just think of the range of stuff we could be standing on right now and what kind of story that can tell us about life you're almost 2000 years ago. they've du: almost 2000 years ago. they've dug boreholes _ almost 2000 years ago. they've dug boreholes to _ almost 2000 years ago. they've dug boreholes to monitor- almost 2000 years ago. they've dug boreholes to monitor what l dug boreholes to monitor what is happening, and at teesside university, they are analysing soil samples.— soil samples. specifically we're looking _ soil samples. specifically we're looking at - soil samples. specifically| we're looking at moisture levels, total carbon, total nitrogen, the chemistry and microbiology changes that go on with the drying out of that heat area.— heat area. and if it does continue _ heat area. and if it does continue to _ heat area. and if it does continue to dry - heat area. and if it does continue to dry out, - heat area. and if it does | continue to dry out, what heat area. and if it does - continue to dry out, what does that mean for the archaeological remains? they will disappear. _ archaeological remains? they will disappear. we _ archaeological remains? they will disappear. we will - archaeological remains? tie: will disappear. we will lose our heritage. it will disappear. we will lose our heritage.— our heritage. it isn't 'ust roman remains �* our heritage. it isn't 'ust roman remains at h our heritage. it isn'tjust roman remains at risk. | our heritage. it isn'tjust - roman remains at risk. there are reckoned to be up to 22,000 archaeological sites in uk peatlands. peatland represents such a small part of the ecology of britain, but the stories that they can tell a massive, and it has such a big implication notjust for our implication not just for our personal implication notjust for our personal history but also our climactic history, and our environmental history, and we need to protect data. who environmental history, and we need to protect data. who knows what else will _ need to protect data. who knows what else will be _ need to protect data. who knows what else will be lost _ need to protect data. who knows what else will be lost unless - what else will be lost unless these sites are preserved? justin rowlatt, bbc news, hadrian 's wall. ten days from now, the sporting world will be looking to china again as the beijing winter olympics begin. it comes almost two years after covid started in the country, and with the highly infectious 0micron variant spreading to more places every day. officials have imposed a strict 0lympic bubble isolation system to control the spread and decided not to sell tickets to the public. china correspondent stephen mcdonell asked the skating enthusiasts of the host city how they felt about this. screaming. the olympics is expected to produce a boom in winter sports here, sports which in the past haven't really involved mass participation. ice skating, though, is something of an exception. there have been scenes like this in cities across the north of china for quite a while now. really? you can see there are plenty of people enjoying themselves today. everyone we've spoken to says they're really looking forward to the olympics, and that they have faith that officials can still control the coronavirus. however, we are yet to see the 0micron variant really take off here, so that could change. a runaway wallaby which evaded capture for nearly three weeks has finally been caught and returned home. ant, named after tv host ant mcpartlin, is now reunited with his brother, dec. jake zuckerman has the story. finally, after three weeks on the run, here we have ant the wallaby. fist the run, here we have ant the wallab . �* ., , the run, here we have ant the wallab . �* . , ., wallaby. at last, the moment the 'd wallaby. at last, the moment they'd been _ wallaby. at last, the moment they'd been waiting _ wallaby. at last, the moment they'd been waiting for - wallaby. at last, the moment they'd been waiting for afterl wallaby. at last, the moment| they'd been waiting for after a long and frustrating chase. it's just overwhelming, really. think, three weeks, we had almost got to the point where we didn't think we would ever see him again.— we didn't think we would ever see him again. since escaping from the farm _ see him again. since escaping from the farm at _ see him again. since escaping from the farm at albion - from the farm at albion lincolnshire on january five, ant has evaded capture time after time. ant has evaded capture time aftertime. he ant has evaded capture time after time. he has kept one hop ahead of his pursuers and even skipped town when it looks like he was caught in this trap. weirdly, i've actually got experience of catching two wallabies previously, so i thought, i've got something to bring to the party. and sure enough, yeah. it bring to the party. and sure enough. yeah-— bring to the party. and sure enough, yeah. it was great to see him there, _ enough, yeah. it was great to see him there, we _ enough, yeah. it was great to see him there, we knew- enough, yeah. it was great to see him there, we knew that| enough, yeah. it was great to i see him there, we knew that the trap we — see him there, we knew that the trap we had got this time was far more _ trap we had got this time was far more substantial and better suited — far more substantial and better suited to — far more substantial and better suited to larger animals. but now he's _ suited to larger animals. but now he's back _ suited to larger animals. pm now he's back home waiting to be reunited with his brother, dec. , , ., be reunited with his brother, dec. ,,., ., ., _ dec. this is our wallaby enclosure. _ dec. this is our wallaby enclosure. can't - dec. this is our wallaby enclosure. can't show. dec. this is our wallaby i enclosure. can't show you dec. this is our wallaby - enclosure. can't show you in the enclosure at the moment because ant is resting following his escapade. he's got plenty of food and water in there, we keep check on him to make sure he is ok, and he will have to stay there until that gives him the all clear. thankfully, ant seems unharmed by his experience, which has seen him become a local celebrity. seen him become a local celebrity-— celebrity. other than the little knock _ celebrity. other than the little knock on _ celebrity. other than the little knock on the - celebrity. other than the little knock on the nose, j celebrity. other than the i little knock on the nose, he looks to be a picture of health. he has grown quite a lot, he has clearly had some decent diet out and about, but he is certainly none the worse for wear. he is certainly none the worse for wear-— for wear. volunteers have reinforced _ for wear. volunteers have reinforced the _ for wear. volunteers have reinforced the fences - for wear. volunteers have i reinforced the fences around the wallaby enclosure, and they are hoping this is the last time ant manages to get the jump time ant manages to get the jump on them. time ant manages to get the jump on them-— time ant manages to get the jump on them. sounds like he has had a _ jump on them. sounds like he has had a great _ jump on them. sounds like he has had a great time - jump on them. sounds like he has had a great time out - jump on them. sounds like he has had a great time out and l has had a great time out and about. i will be back with the top stories next. hello. tuesday promises more of the weather we've been so used to lately — largely dry, but often cloudy. the satellite picture shows this pale grey colour here — that's the sheet of low cloud that's been with many of us for the last few days. this bright white cloud out towards the west is the first sign of the frontal systems that will eventually get things moving and bring about something of a change. but for tuesday morning, most places starting off grey and cloudy, some mist and fog patches, too. the fog should tend to lift as the day wears on, as the breeze picks up a little. best chance of sunshine perhaps for north east wales, the west midlands, north east england, but more especially for northern ireland, for southern and eastern scotland, where the breeze really will be picking up, turning that cloud over and breaking it up. some spots of rain into northwest scotland. temperatures ranging from just 3—4 celsius in parts of eastern england, to maybe 8—9 in western scotland and northern ireland. now as we head through tuesday night, we'll see one band of cloud and a few spots of rain pushing south towards — a very weak weather front. 0ur big area of cloud will start to retreat southwards, so we will see a few more clear breaks developing that could allow temperatures to drop relatively close to freezing — at the same time, there'll be more of a breeze. so i think quite a few places will stay frost—free, there'll be a few pockets of frost here and there. but wednesday morning starts under the influence of this area of high pressure — the high really has been with us for quite a few days now. but a weather system approaching from the northwest will start to get things moving and change things — and certainly, the wind will be strengthening through the day across northern ireland and scotland, gales in exposed northwestern areas later with outbreaks of rain pushing in. much of england and wales dry, a little more in the way of sunshine and slightly higher temperatures, as well, 8—10 celsius. now as we go through wednesday night and on into thursday, we push this frontal system southwards, we'll see some really strong winds for a time around the far north of scotland. that weatherfront, as it gets into the south, well, not much rain left on it, but maybe a legacy of cloud and drizzle for a time across southwest england and the channel islands. however, for most of us on thursday, we will see quite a lot more in the way of sunshine, a few showers into the north of scotland. temperatures not doing too badly, actually, 7—12 celsius. friday will bring the return of the cloud, pushing in from the west — but it will be quite mild, quite breezy and dry for most. piers edwards, bbc news, 0lembe stadium, yaounde. this is bbc news with the latest business headlines for viewers in the uk and around the world. european gas prices spike and global markets go on a roller—coaster ride as russia—ukraine tensions ratchet up. a few hours ago president biden held talks with key european allies as western leaders weigh up sanctions and energy security. 0ne former american defense secretary gave bbc world news his thoughts on mr biden's approch. he has taken a number of steps to send an important signal to the russians about the price they are going to pay. 0n sanctions, i would give him the same opportunity to make that judgement. unilever — the maker of everything from marmite to dove soap will cut thousands ofjobs in over 100 countries