this is bbc news. i'm rebecca jones with the latest headlines. the us warns that the russian troop build—up near ukraine is the largest since the cold war — as attempts to find a diplomatic solution continue. the downing street lockdown parties report is now expected to be delivered before the metropolitan police inquiry ends. five states declare emergencies and more than 5,000 flights are cancelled, as the us east coast braces for a major blizzard to hit the region. a more detailed study is under way after pilot research finds some people with long covid may have hidden damage to their lungs. ash barty wins the australian open tennis to become first home winner in 44 years. and the cold water swimmers who swear that a dip in the icy sea