Trump transition live updates: Trump names longtime ally Brooke Rollins as secretary of agriculture

On "Fox News Sunday," Florida Rep. Mike Waltz -- President-elect Donald Trump's pick for national security adviser -- confirmed he met with Jake Sullivan, who currently holds the role in President Joe Biden's administration, and said that their teams are working together.

Waltz appeared to defend Biden's weapons policy reversals for Ukraine, though he called the moves "an escalation."

"Look, this is a clear escalation. And the concern has been, where is this escalation going?" Waltz said. "This was in response to, in large part, to North Korea sending troops. We've now responded by allowing these strikes deeper into Russia."

-ABC News' Fritz Farrow

President-elect Donald Trump announced Saturday that Brooke Rollins is his pick to lead the Department of Agriculture.

The seat requires Senate approval.

Rollins served in the first Trump administration, first as the assistant to the president for intergovernmental and technology initiatives and then later as the acting director of the Domestic Policy Council.

After Trump left office, she became the president and CEO of the America First Policy Institute, a conservative right-wing think tank which is made up of former Trump staff members that promotes his agenda.

-ABC News' Kelsey Walsh, Lalee Ibssa and Soo Rin Kim

President-elect Donald Trump met with the new NATO Secretary General Mark Rutte Friday night at Mar-a-Lago, a NATO spokesperson said.

"They discussed the range of global security issues facing the Alliance," they said.

"The Secretary General and his team also met with Congressman Mike Waltz and members of the President-elect's national security team," the spokesperson added.

-ABC News' Lalee Ibssa, Kelsey Walsh and Soo Rin Kim

President-elect Donald Trump has nominated Scott Turner to lead the Department of Housing and Urban Development.

Turner, a former NFL player and Texas lawmaker, served in the White House during Trump's first term as the first executive director of the White House Opportunity and Revitalization Council, "helping to lead an Unprecedented Effort that Transformed our Country's most distressed communities," Trump said in a statement Friday.

In that role, Turner worked with former HUD Secretary Ben Carson on boosting economic development in "Opportunity Zones" across the country, created by the 2017 Tax Cuts and Jobs Act, which allowed people to invest in low-income areas and temporarily defer tax on eligible gains.