What the former secretary of energy thinks about Iran, climate change and nuclear security

This week, Iran tested a ballistic missile — prompting a sharp reaction from National Security Adviser Michael Flynn and, then, from President Donald Trump.

“Iran has been formally PUT ON NOTICE,” the president tweeted on Thursday. While he did not immediately discuss plans for policy changes, his comments have prompted speculation that the Iran nuclear deal could be under threat.

Ernest Moniz, a nuclear physicist who helped negotiate the Iran deal and served as secretary of energy in the Obama administration, pointed out that Iran didn’t actually violate the terms of the agreement when it fired the missile. “The nuclear deal was not about missiles,” Moniz said. Rather, it aimed to halt the development of nuclear weapons in Iran. “When all is said and done, that is the existential threat — whether to our allies in the region or to us directly.”

Moniz added that the United States can mount a robust rebuttal to Iranian actions, but he hopes that its response will not undermine the years of work that went into the nuclear agreement.

Related: A US confrontation with Iran could be deadly for American troops in Iraq

The nuclear deal is among a number of policies that Moniz worked on in the Obama administration, and it’s not the only one he thinks could see some changes under Trump. When asked about the Paris climate agreement, which lays out a plan for reducing greenhouse gas emissions, Moniz acknowledged that it, too, could be jeopardized. But he feels that American states, cities and companies can still uphold the agreement on their own.

Related: Canada is moving ahead with an aggressive carbon reduction plan

“I think the Paris Agreement was a watershed moment,” Moniz said. “But I don’t want to imply by that, that, without the Paris Agreement, we would not still keep going in this direction of a low-carbon future.”

In general, the former secretary of energy emphasized stability and continuity between the Obama and Trump administrations, in spite of major policy changes that Trump has already made through executive orders. Moniz, who also worked for the Clinton administration, pointed out that a little over 100 political appointees left the Department of Energy as part of the transition. By contrast, about 114,000 people work for the DOE as civil servants, scientists, staff and contractors — and most of them are likely to stick around.

As for Moniz? He returned to his post as a professor at the Massachusetts Institute of Technology in late January. Meanwhile, his likely successor, Rick Perry, was confirmed by a Senate committee this week. Perry now faces a confirmation hearing before the full Senate.