The 2015 deal Iran struck with the United States and five other countries to suspend its nuclear program for 10 years in exchange for sanctions relief did not occur because Washington and Tehran had suddenly become friends.

"We did not trust the U.S. and the United States obviously did not trust us," recalled one of the deal's architects, Iran Foreign Minister Mohammed Javad Zarif, to journalist and television host Charlie Rose at Asia Society on Wednesday.

"It was 'trust but verify' in principle," Rose said, alluding to the Russian expression famously used to describe the U.S.-Soviet relationship.

"It was 'don't trust but verify'" said Zarif.

In spite of this fraught relationship, the two-year-old deal remains firmly in place — for now. U.S. President Donald Trump — who has called the deal agreed to by his predecessor Barack Obama an "embarrassment to the United States" — has hinted that he may declare Iran non-compliant during the next scheduled review on October 16. Such an announcement would allow Congress to reimpose sanctions and, in effect, curtail Washington's participation in the deal.

In his conversation with Rose, Zarif indicated that Iran plans to hold up its end of the bargain.

"If Congress behaves, [then] 6 years from now, 8 years from the signing of the agreement, we will be ratifying the additional protocol," Zarif said. "Additional Protocol is the most intrusive inspection regime that’s available in the international community."

As a result, Zarif added, Iran would become a normal member of the non-proliferation treaty obliged not to pursue nuclear weapons. "Nuclear weapons are not to be considered as part of our national interests," he said.

Zarif claimed to not know why the Trump administration may wish to withdraw.

"This administration leaves people guessing," he said. "Unpredictability might be an asset in foreign policy. Unreliability isn't."

Throughout the lively and at times combative discussion with Rose — the veteran journalist even reassured the diplomat that they were "still friends" after one particularly heated exchange — Zarif deflected criticism of Iran for its role in Syria and Yemen. He also accused the United States and President Trump of hypocrisy for criticizing Iran's system of government while maintaining alliances with authoritarian regimes in the region.

"It’s interesting that all of President Trump’s allies have never seen a ballot box and he calls us a dictatorship.”

"We derive our legitimacy and our power from the people. We do not derive our legitimacy from the beautiful military equipment we get from the United States.”