°®Âþµº

The United States should remain in the nuclear deal negotiated during former President Barack Obama administration, US Defence Secretary James Mattis said on Tuesday.

During a congressional hearing, Sen. Angus King of Maine asked Mattis if he thinks it’s in the national security interests of the US to stay a part of the international accord which curbs Iran's ability to build a nuclear arsenal.

Mattis said, "Yes, senator, I do."

US President Donald Trump has branded the deal as the worst agreement ever negotiated by the United States.

Trump has repeatedly said that he's inclined not to certify Iranian compliance after having twice found the country compliant at earlier deadlines.

Denying certification could lead the US to reintroduce sanctions, which could potentially lead Tehran to walk away from the deal or restart previously curtailed nuclear activities.

Officials have speculated that Trump may use the 15 October deadline for certifying to Congress whether Iran is in compliance with the nuclear deal to either declare Tehran in violation or determine that the agreement is no longer in the national security interest of the US.

Democrats in Congress are becoming increasingly anxious that Trump's distaste for the Iran nuclear deal will lead him to abandon the accord and risk the ability to contain Tehran's nuclear programme.

Mattis' statement gave them a strong argument in the discussion.

"If we can confirm that Iran is living by the agreement, if we can determine that this is in our best interest, then clearly, we should stay with it," Mattis said.

"I believe, at this point in time, absent indications to the contrary, it is something the president should consider staying with."

Sen. Tom Cotton, R-Ark., who dined with Trump on Monday evening along with several other lawmakers, said Tuesday that he discussed Iran with the president.

"He didn't tell me, he said he's made a decision but he's not telling anyone. I strongly urged him to not certify the deal," Cotton said.

Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said last month that Iran is committing to its obligations under the nuclear agreement, known officially as the Joint Comprehensive Plan of Action.

He emphasised that his concern is about Iran's behaviour in other areas, such as its development of ballistic missiles and its support for extremist militias across the region.

Dunford declined to say publicly what advice he has given Trump on whether to recertify Iran's compliance with the nuclear deal.

Iran has ruled out any renegotiation of the agreement and has said that any relinquishment of the deal would lead to the immediate resumption enrichment of uranium.

Tehran also has reiterated that it has no intention ever of obtaining nuclear weapons, but the US and Israel are among the countries that do not accept those assurances, citing Iran's past nuclear activities.