Andrei Pungovschi/Bloomberg via Getty Images(NEW YORK) -- More than six months after Russian President Vladimir Putin launched an invasion into neighboring Ukraine, the two countries are engaged in a struggle for control of areas throughout eastern and southern Ukraine. Ukrainian President Volodymyr Zelenskyy, whose forces began an offensive in August, has vowed to take back all Russian-occupied territory. But Putin in September announced a mobilization of reservists, which is expected to call up as many as 300,000 additional troops. Here's how the news is developing. All times Eastern: Dec 15, 12:48 PM EST Putin purportedly planning major new year offensive: Report Ukraine's defense minister is claiming in a news interview that Russian President Vladimir Putin is planning a major new offensive to launch in the new year. Oleksii Reznikov told the British newspaper The Guardian that emerging evidence indicates the Kremlin is preparing a broad new offensive possibly in February. Reznikov said the new offensive is part of a second wave of a mobilization of 300,000 reservists Putin announced in September. "The second part of the mobilization, 150,000 approximately, started their training courses in different camps," Reznikov said. "The [draftees] do a minimum of three months to prepare. It means they are trying to start the next wave of the offensive probably in February, like last year. That's their plan." News of the possible offensive comes after a series of setbacks the Russians have had on the battlefield, including a botched attempt in March to the take Kyiv, the Ukrainian capital. Dec 14, 10:20 AM EST US Air Force vet released from Russian captivity A U.S. Air Force veteran from Minnesota was freed Wednesday from Russian-controlled territory and told ABC News he survived being beaten and electrocuted by his captors. Suedi Murekezi, 35, was freed in a war gray zone just outside Zaporizhzhia in southern Ukraine. A prearranged two-hour cease-fire was called to allow an exchange of prisoners of war. Murekezi and other prisoners of war were brought out of Russian-controlled territory as part of the exchange. Following his release, Murekezi was seen clutching a Ukrainian flag given to him by a Ukrainian military intelligence officer. Murekezi was arrested in June when he was falsely accused by the Russians of being a member of the CIA, he said. He said he was later released; however, he was stuck in Donetsk, a city in Russian-controlled territory, because he was without his U.S. passport. In an exclusive interview with ABC News, Murekezi said he felt "trapped" in Donetsk and lived under intense uncertainty about his future. He said he was relieved and happy to be back in Ukrainian-controlled territory, a free man in the country where he has lived for years, working in cryptocurrency. What he is looking forward to most when he gets back to Minnesota? "A peanut butter sandwich," Murekezi said. -ABC News' Tom Soufi Burridge, Dada Jovanovic, Natalia Kushniir and Kuba Kaminski Dec 14, 10:28 AM EST Drone attacks launched on Kyiv Two waves of drone attacks were launched before dawn on Wednesday in Kyiv. President Volodymyr Zelenskyy said that every drone was shot down and urged residents of Ukraine's capital city not to ignore air raid warning sirens. "This morning has started with 13 Shahed drones attacking. All 13 were downed by our air defense. Good job. Thank the air defense and please don't ignore the air raid sirens," Zelenskyy said in a statement following the drone attacks. Kyiv Mayor Vitaliy Klitchko also confirmed the attack and urged residents to take shelter underground. The latest attack comes as the U.S. is preparing to approve sending Patriot missile defense systems to Ukraine and that these plans could be approved by President Joe Biden as early as this week. United States Defense Secretary Lloyd Austin also has to sign off on the transfer before it goes to the White House but, if approved by Biden, the transfer of the advanced air defense systems would meet a long-standing request from Ukraine. A senior Ukrainian Defense official told ABC News on Tuesday that the Patriots "will be a game changer." -ABC News' Tom Soufi Burridge Dec 13, 3:36 PM EST US preparing to send Patriot air defense missiles to Ukraine Two U.S. officials confirm that the U.S. has prepared plans to send Patriot air defense missile systems to Ukraine that could be approved by President Joe Biden as early as this week. If approved by Biden, the transfer of the advanced air defense systems would meet a long-standing request from Ukraine. The U.S. has stressed the importance of Ukraine getting additional air defense systems in the coming months but has worked with other countries on alternative systems other than the Patriot. The Patriot missile systems to be given to Ukraine will come from U.S. inventories under the presidential drawdown authority, according to officials. Another one of those announcements is expected to be announced on Thursday, though it is unclear if the Patriots will be included as part of that package. If Biden approves the Patriot systems, then the training of Ukrainian troops will begin in Germany a few weeks later, officials said. Defense Secretary Lloyd Austin must sign off on the transfer before it goes to the White House. -ABC News' Luis Martinez Dec 13, 3:17 PM EST Ukraine to get 30 upgraded Soviet-era tanks from Czech Republic next year Soviet-era tanks are getting new optics, armor, and more at a Czech facility in Šternberk, thanks partly to the efforts of Ukrainian refugees working there. Around 150 people have been hired by Excalibur Army in an effort to modernize old military equipment from around the world, which will then be shipped to Ukraine after months of work on upgrades. According to the company's commercial director, Richard Kuběna, it is concentrating on a large order to modernize up to 120 T-72 tanks, which the U.S. and the Netherlands governments ordered and paid 2.2 billion crowns for. The tanks were ordered initially from Šternberk by an African country. However, after negotiating with the U.S., E.U., and Czech Ministry of Defense, they decided to give the tanks to Ukraine, Kuběna said. "Next week, the first five units of tanks for Ukraine will be received, we would like to deliver 18 units by the end of the year," noted Kuběna. Kuběna said he would like to Dec 13, 6:47 AM EST Russian withdrawal 'out of the question' A Kremlin official said on Tuesday that Russia's withdrawal from Ukraine was "out of the question." A reporter asked Kremlin spokesman Dmitry Peskov for comment on Ukrainian President Volodymyr Zelenskyy's proposal that Russia start to pull out forces from Ukraine before Christmas. Peskov was also asked whether Moscow was ready to do so before the end of this year. "This is out of the question," Peskov said. Dec 11, 7:56 PM EST Biden speaks with Zelenskyy about recent security assistance packages: White House President Joe Biden spoke with Ukrainian President Volodymyr Zelenskyy on Sunday to discuss continued support for Ukraine's defense amid Russian attacks on critical infrastructure, according to a White House readout of their call. "President Biden highlighted how the U.S. is prioritizing efforts to strengthen Ukraine's air defense through our security assistance, including the December 9 announcement of $275 million in additional ammunition and equipment that included systems to counter the Russian use of unmanned aerial vehicles," the White House said. "President Biden also highlighted the November 29 announcement of $53 million to support energy infrastructure to strengthen the stability of Ukraine's energy grid in the wake of Russia's targeted attacks," it added. -ABC News' Justin Ryan Gomez Dec 09, 12:05 PM EST Treasury sanctions 4 Russians for carrying out human rights abuses The U.S. Department of Treasury issued sanctions against four Russians accused of forcibly seizing personal data and