National security advisor Jake Sullivan said President Biden was doing what he could to "strengthen" the position of Ukraine before he leaves office.

Watch Major Garrett's full interview with National Security Adviser Jake Sullivan, a portion of which aired on Dec. 1, 2024 on "Face the Nation with Margaret Brennan."

President-elect Donald Trump tapped Waltz, a Florida congressman and the first Green Beret to serve in Congress, to be his national security adviser in the upcoming administration. This was Waltz’s first television appearance since being picked, though Waltz is currently the member of Congress with the most appearances on Fox News.

Outgoing National Security Adviser Jake Sullivan denied reports that the Biden administration is considering returning nuclear weapons to Ukraine, after the country relinquished its stockpile three decades ago after the fall of the Soviet Union.