Trump has tapped Rep. Mike Waltz, Republican of Florida, to be his national security adviser, multiple sources said.

Waltz was at Mar-a-Lago on Monday, sources said.

The national security adviser is appointed by the president without Senate confirmation.

Waltz is a former Green Beret and China Falcon who became a key Trump surrogate, criticizing the Biden-Harris foreign policy record during the campaign.

The Florida Republican serves on the Intelligence, Armed Services and Foreign Affairs committees.

He has supported aid to Ukraine in the past but demanded “conditions” including increased spending from European allies, increased oversight of funds and linking aid to measures border security.

Waltz, who visited Ukraine, sharply criticized the Biden administration’s Ukraine policy, criticizing the White House and its allies for failing to provide Ukraine with more lethal aid – like MiG fighter jets – earlier in the conflict.

Before running for office, Waltz served in various national security policy roles in the Bush administration, the Pentagon and the White House.

Trump has had four different national security advisers during his first term, aside from those who served very briefly: Michael Flynn, HR McMaster, John Bolton and Robert O’Brien.

-Rachel Scott, Benjamin Siegel, John Santucci and Katherine Faulders of ABC News