NEW YORK – President Hassan Rouhani said Monday that America will pay a “high cost” if U.S. President Donald Trump makes good on his threats to scrap the Iran nuclear deal.

Speaking in an exclusive interview with CNN in New York, Rouhani said: “Exiting such an agreement would carry a high cost for the United States of America, and I do not believe Americans would be willing to pay such a high cost for something that will be useless for them.”

Rouhani said such an action by the Trump administration “will yield no results for the United States but at the same time it will generally decrease and cut away and chip away at international trust placed in the Unites States of America.”

The next major deadline comes in October, when Trump will decide whether to certify that Iran is complying with the agreement, known as the Joint Comprehensive Plan of Action (JCPOA). If he does not, Congress has 60 days to decide whether to re-impose sanctions waived under the deal.

Rouhani said Iran was ready to respond to the possibility of Trump walking away from the agreement.

“Given that Mr. Trump’s actions and reactions and policies are somewhat unpredictable, we have thought long and hard about our reactions,” he said.

He said any riposte from Iran would come “quite swiftly” and “probably within a week,” adding that “if the US wants to increase the tensions it will see the reaction from Iran.”

Rouhani, who was re-elected by a popular vote to a second presidential term earlier this year, was a key architect of the 2015 nuclear agreement with the United States, the European Union and other partners.

The deal led to the lifting of most international sanctions against Iran in return for curbs on its nuclear program.

The agreement is expected to feature high on the agenda at this week’s UN General Assembly in New York, which both Rouhani and Trump are attending.

On Thursday, Trump again attacked the agreement, calling it “one of the worst deals I have ever seen.”

Rouhani warned of the diplomatic precedent that would be set by pulling out of the Iran agreement, especially with regard to North Korea.

“I think what the Iranian experience shows is a good experience that can be replicated elsewhere and executed elsewhere,” he said.

“But keep in mind please that if the United States wishes to withdraw from the JCPOA, why would the North Koreans waste their time in order to sit around the table of dialogue with the United States, because they would think perhaps after years of talks and a potential agreement the next U.S. administration could step over or pull out of the agreement.”

On the war in Syria, Rouhani stopped short of declaring an outright victory for the Syrian government, which Iran has supported on the ground, but described Tehran’s intervention as a success.

“Our actions were successful and today we are witnessing the final stages of the defeat of ISIS” he said, before calling for eventual elections in Syria.

“The future of Syria will be determined by talks and ultimately the opposition must reach an agreement with the government and the will of people would be the ballot box should ultimately determine what happens,” Rouhani told CNN.

CNN also asked Rouhani about Iran’s position regarding the current crisis in Myanmar, where the government has been accused by the UN of ethnically cleansing Rohingya Muslims. The Myanmar government has denied this, claiming security forces are carrying out counter attacks against “brutal acts of terrorism.”

Rouhani said that Myanmar should be condemned and that aid should be forwarded to Bangladesh, where hundreds of thousands of Rohingya refugees have fled in recent weeks.

He also said he shared concerns that ISIS and al Qaeda fighters in Syria and Iraq could move across to Bangladesh and Myanmar to exploit the Rohingya crisis.

CNN also asked about foreign nationals and dual citizens detained in Iranian jails, including Nazanin Zaghari-Ratcliffe, a British-Iranian dual citizen who was arrested in 2016 and sentenced to five years’ imprisonment, and the Iranian-American dual citizens Siamak Namazi and his father Baquer Namazi, who have been imprisoned since 2015 and 2016, respectively, and were each sentenced to 10 years.

Rouhani said in an aside that he had his own views on the subject of detained foreigners and dual citizens, but that he was obliged to follow the Iranian constitution which had enshrined the separation of powers between the executive and the judiciary.