Pulling out of the Iran agreement is not a political winner for Mr. Trump beyond his base. Sixty-three percent of Americans surveyed by CNN said the United States should not scrap the deal, while only 29 percent said it should.
But Mr. Trump’s decision has strong support among select constituencies, particularly national security hawks and advocates of Israel. And it fits Mr. Trump’s worldview that the United States has been rolled by allies and adversaries alike in essentially every international agreement reached in recent decades.
Some veteran diplomats said Mr. Trump may yet find moments where he will scale back his more radical impulses at the urging of advisers. They point to his decision last year to send more troops to Afghanistan rather than pull out, as he had previously proposed. And he may yet avoid tearing up Nafta or imposing tariffs on European allies by the June 1 deadline he has set.
“I believe his foreign policy will continue to be a mix of the two,” said Zalmay Khalilzad, who served as ambassador to the United Nations under Mr. Bush. “His instinct and values are what he committed to during his campaign but will continue to selectively adapt to circumstances and transact based on both.”
That tension will be especially acute in coming weeks even as Mr. Bolton and Mr. Pompeo are still putting together their teams and settling into their roles. Ms. Zegart noted that Mr. Trump is now engaged in complicated and dangerous nuclear standoffs with both Iran and North Korea, as well as a burgeoning trade war with China, the trade disputes with allies and a confrontation with Syria, all at the same time.
“With a list that long and a policy process that undisciplined, the odds of a policy breakdown are higher than a breakthrough,” she said.
Process, of course, has never been Mr. Trump’s top priority. And he may find himself on the opposite side even of his new empowering advisers. Mr. Bolton, for instance, has for years been a skeptic of the sort of diplomatic initiative that Mr. Trump is embarking on with North Korea and will most likely make the case that it is not a fruitful venture if it does not seem to be working.
Mr. Trump may then once again have to choose between his advisers and his instincts. “Trump is making unilateral decisions with long-term consequences for U.S. foreign policy with little grasp of the issues,” Mr. Goldgeier said. “But he’s delivering on his campaign promises and undoing Obama’s legacy, both of which are important to him.”