National Security Adviser Jake Sullivan said Sunday that the Biden administration will continue to push forward during its final 71 days in the White House to achieve ceasefires in Gaza and Lebanon, and to support Ukraine.

“Our approach remains the same as it has been for the last two and a half years, which is to put Ukraine in the strongest possible position on the battlefield so that it can ultimately be in the strongest possible position at the negotiating table,” Sullivan told host Margaret Brennan on CBS’s “Face the Nation.”

President-elect Donald Trump has threatened to cut off aid to Ukraine soon after taking office, and has claimed he will end the war started by Russian President Vladimir Putin in a day, without specifying how. His son Donald Trump Jr. on Saturday shared a video on Instagram mocking Ukraine.

“It should be up to Ukraine to decide for the sake of its sovereignty and territorial integrity when and how to come to the negotiating table,” Sullivan said Sunday. “It should be up to the United States and the coalition of nations we have built to continue to provide Ukraine with the means to defend itself against Russia’s brutal aggression.”

Sullivan added that President Joe Biden and Trump plan to meet on Wednesday to discuss key domestic and foreign policy issues, including “what’s happening in Europe, Asia and the Middle East.” He stressed that by January 20, Biden plans to spend the full amount of resources and aid for Ukraine authorized by Congress, as well as make the case to the incoming administration that the United States should continue to provide that aid. “Withdrawal means more instability in Europe, and ultimately, as the Japanese prime minister said, if we walk away from Ukraine in Europe, the question of America’s commitment to our allies in Asia will grow,” Sullivan continued. Asked whether Russia would face consequences for interfering in the US election, he said that helping Ukraine “already does a lot of things to impose costs on Russia,” and emphasized US sanctions on Russia.

Sullivan also spoke about how U.S. involvement in the Middle East conflict might change with the next administration, emphasizing that at this point, Hamas is refusing to reach a ceasefire with Israel in Gaza. “What we need to do is get the rest of the world to continue to increase the pressure on Hamas to come to the table to negotiate an agreement in Gaza, because the Israeli government has said it is prepared to take an interim step in that direction,” Sullivan told Brennan.

Sullivan said he believes that “at some point, the Israeli government wants to make a deal to bring its citizens home. I don’t think they’re doing it for American policy. I think they’re doing it to try to secure Israel, and I expect in the coming weeks we’ll see progress.” He also said the United States has been actively engaged in discussions with the Israeli government regarding its conflict with Lebanon.