Amidst the uncertainty facing the Iran nuclear deal ahead of an Oct. 15 deadline, Defense Secretary Jim Mattis, who testified before the Senate Armed Services Committee on Tuesday said the United States should remain in the Iran nuclear deal. Mattis testimony was also shared by Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford during the hearing.

Questioned by Sen. Angus King, on whether he thought there was a “national security interest” to remain in the Iran deal, Mattis replied “Yes, sir. I do”.

President Trump has been highly critical of the Obama-era deal, a pact Trump described as the “worst deal” he’s ever seen while speaking at the UN General Assembly last month.

Speaking on the deal late last month, Secretary of State Rex Tillerson suggested that the president had made his decision on whether to withdraw from the agreement but had not shared that decision “externally.”

Trump is yet to make his decision on whether the deal will be recertified by the Oct. 15 deadline public. A denial of certification could lead to the reintroduction of sanctions by the U.S., and could invariably force Iran to abandon the deal or even relaunch some nuclear activities it had engaged in prior to the 2015 agreement.

Contrary to Trump’s claims, Dunford testified Tuesday that Iran is following the requirements of the deal.

He said, “The agreement right now, what I testified to last week, Iran is not in material breach of the agreement. And I do believe the agreement, to date, has delayed the development of nuclear capability by Iran.”

Mattis in a slightly different tone assured that, while he believes it is in the best interest of the U.S. to abide by the nuclear deal, the administration is “very alert” to any “cheating” by the Iranians.

He said, “The amount of misconduct, I would call it, internationally, whether it be with ballistic missiles, rhetoric, support to terrorists, threats to our friends, Arab and Israel in the region by Iran, are areas that they are open to a great deal, I think, of censure by the international community. We are not naive about their agreement on the nuclear issue, and we are being very alert to any cheating on that right now.”