Brian Hook, the State Department's special envoy for Iran and one of the few national security officials to survive the turmoil in the foreign policy team through most of President Donald Trump's term, is stepping down from his post, Secretary of State Mike Pompeo announced Thursday.

The departure of Hook, 52, appears to bury any remaining chance of a diplomatic initiative with Iran before the end of Trump's term. In the four years during which Hook became the face of U.S. sanctions against Tehran, Hook also held out the possibility of resuming direct talks, the way the Obama administration had.

But to the Iranians — and to some of his critics in Europe and at home — Hook was merely a defender of a policy meant to break the country and force it to the table to renegotiate a deal they had reached, and complied with, with the Obama administration in 2015.

Hook will be succeeded by Elliott Abrams, a conservative foreign policy veteran and Iran hard-liner who is currently the State Department's special representative for Venezuela. He will continue to hold that job as well, Pompeo said.

"There is never a good time to leave," Hook said in an interview, because the confrontation with Iran had become a perpetual series of provocations, responses and efforts to change Tehran's behavior.

He departs with his main goal still elusive. Trump's decision to leave the Iran nuclear deal has not forced the Iranian government to change its conduct, but it did lead to a public effort to reconstitute its nuclear production facilities. Hook insisted that with more time, Iran's economic devastation, largely because of U.S.-led sanctions imposed after Trump abandoned President Barack Obama's nuclear deal, would force the country to give up all of its ability to enrich nuclear fuel.

"Sometimes it's the journey and sometimes it's the destination," Hook said. "In the case of our Iran strategy, it's both. We would like a new deal with the regime. But in the meantime, our pressure has collapsed their finances.

"By almost every metric, the regime and its terrorist proxies are weaker than 3½ years ago," he added. "Deal or no deal, we have been very successful."

Many disagree, including Wendy Sherman, the former No. 3 at the State Department and the chief negotiator on the Iran deal for Obama. Sherman, in a response to a presentation by Hook at the Aspen Security Forum on Wednesday, called the administration's approach to Iran "all tactics, no strategy."

Her complaint, sometimes heard among career officials inside the State Department as well, is that the sanctions approach is a way of beggaring the country, but not promoting reform or building a relationship.

Sen. Lindsey Graham, R-S.C., a regular adviser to Trump on foreign policy, praised Hook while conceding that "the window on a replacement" for the nuclear deal "is probably closing before the election." He added, however, that "after the election, it is a win-win proposal."

Graham said Hook had done "a superb job" of building U.S. alliances against Iran with Arab states in the Persian Gulf.

"He was a steady hand in choppy waters," he said, adding: "He is a survivor — that's no small feat in Trump world."