Following up on U.S. National Security Advisor John Bolton’s harsh rhetoric regarding Iran, its aggression and its nuclear ambitions, Senior Policy Advisor to the Secretary of State and Special Representative for Iran Brian Hook elaborated on America’s thinking when it comes to Tehran.

In a special briefing on Tuesday as part of this week’s U.N. General Assembly meeting and related proceedings in New York, Hook answered reporters’ questions, including any future U.S. meetings with Iranian leaders.

“When [U.S President Donald Trump] talks and Secretary of State [Mike Pompeo] talks and says that we have an ear open, we are happy to meet and to discuss the kinds of things that we’re seeking and the kinds of things that we’re willing to do in return. This is a regime … this is an aspect of revolutionary regimes which makes it difficult to get to the table,” said Hook.

“Iran historically comes to the table after extensive pressure, and so everything that is being said is being said publicly,” he continued. “There’s been no shortage of tweets from [Iranian President Hassan] Rouhani and [Foreign Affairs Mohammad Javad] Zarif and others, and so it’s all been out in the open.”

With an eye towards Europe, Hook said “we know what a country—we know the different markers of what denuclearization looks like. Storing an atomic archive with an armed guard in the middle of Tehran does not look like you’ve given up your intent to achieve your status as a nuclear-weapons state. And so, I think discovering a half a ton of materials that were protected and preserved made the sunset clauses even more relevant.

“Iran has not earned the trust to have restrictions on its nuclear program lifted, and that was, I think, the most fundamental deficiency of the Iran nuclear deal, is it lifted restrictions on Iran’s nuclear program. Iran has not earned the trust to have those lifted,” said Hook.

Therefore, he stated unequivocably, “our policy is that regardless of what kind of special purpose vehicle or other mechanism is created, the United States will vigorously enforce our sanctions.”

The next round of U.S. sanctions on Iran, which will target its energy production, are set to begin on Nov. 4.