“Their entire strategy is the pressure itself, with the hope that it brings down the government,” Mr. Sullivan said.
For more than a decade, Mr. Bolton advocated “the overthrow of the mullahs’ regime in Tehran.” But he recently told Voice of America that leadership change was “not the objective of the administration.” Mr. Pompeo likewise stopped short of calling for regime change, though he did not mention diplomacy in his speech Sunday at the Ronald Reagan Presidential Library in Simi Valley, Calif.
By contrast, Mr. Pompeo is heavily invested in diplomacy with North Korea, where, as C.I.A. director, he helped lay the groundwork for the Singapore summit meeting and, as secretary of state, has led the negotiations with Mr. Kim’s subordinates. Mr. Bolton took a lower profile on North Korea, in part because he nearly sabotaged the meeting by declaring that the United States should use Libya as a model for ridding North Korea of its nuclear arsenal.
On Iran, however, Mr. Bolton has helped set the tone. On Monday morning, he issued a statement that was every bit as bellicose as Mr. Trump’s, except for being in lowercase letters.
“I spoke to the president over the last several days,” he said, “and President Trump told me that if Iran does anything at all to the negative, they will pay a price like few countries have ever paid before.”
Vali R. Nasr, the dean of the Johns Hopkins School of Advanced International Studies, said: “The endgame for Trump is different than it is for hawks like Bolton and Pompeo. Trump is much more interested in what comes out of it for him personally, in terms of a Nobel Peace Prize.”
Even if Mr. Trump overcame the objections of his staff to pursue a diplomatic opening, experts said it was unlikely Iran would be receptive. His decision to pull out of the nuclear deal has strengthened the hand of hard-liners there. Leaders like Mr. Rouhani, who was once viewed as a moderate, have become more hawkish.