Donald Trump in a second term would likely install loyalists in key positions in the Pentagon, State Department and CIA whose primary allegiance would be to him, allowing him more freedom than in his first presidency to enact isolationist policies and whims, nearly 20 current and former aides and diplomats said.

The result would enable Trump to make sweeping changes to the U.S. stance on issues ranging from the Ukraine war to trade with China, as well as to the federal institutions that implement — and sometimes constrain — foreign policy, the aides and diplomats said.

During his 2017-2021 term, Trump struggled to impose his sometimes impulsive and erratic vision on the U.S. national security establishment.