Yukiya Amano is the head of the International Atomic Energy Agency, which says Iran is sticking to the limits imposed by the 2015 nuclear deal. (Jon Gambrell/AP)

Iran is adhering to the restrictions imposed on its nuclear program under a 2015 agreement, the United Nations agency charged with monitoring the country’s facilities has said in its first report since President Trump refused to certify the Islamic republic’s compliance.

The International Atomic Energy Agency (IAEA) said in a confidential report viewed by Reuters and several other news outlets Monday that Iran’s stockpiles of enriched uranium have not exceeded the agreed limit of 300 kilograms. It also reported that IAEA inspectors were able to gain access to any sites they tried to visit.

The quarterly report marked the ninth successive time the IAEA has attested that Iran is meeting its commitments since the nuclear deal between Iran and six major powers, including the United States, was implemented early last year.

Last month, Trump refused to certify that Iran was keeping up its end of the deal. Although U.S. officials have acknowledged that Iran is in "technical" compliance, they say the country is violating the "spirit" of the landmark agreement to curb its nuclear program in exchange for sanctions being suspended. During his campaign and into his presidency, Trump has been a fierce critic of the agreement, which he calls "the worst deal ever."

Trump declared that the agreement does not serve U.S. national security interests, and he sent it to Congress so lawmakers could “fix” sections he considers not advantageous to the United States. Under U.S. law, Congress faces a Dec. 12 deadline for taking action.

Sens. Bob Corker (R-Tenn.) and Tom Cotton (R-Ark.) are working on legislation that would threaten the reimposition of nuclear-related sanctions if Iran did not meet certain criteria.

So far, however, no legislation has been introduced, and Corker has said they are in no hurry as he tries to come up with a bipartisan plan.

The United States is the only country among the six that negotiated the deal to express dissatisfaction. European diplomats have been lobbying Congress not to make any changes that would jeopardize it.

According to Iranian news reports, Ali Akbar Salehi, the head of Iran’s atomic energy agency, said Sunday that if the deal fails, Iran will take “appropriate measures that will astound” people.

The IAEA’s report provides more ammunition for supporters of the agreement who say the United States will isolate itself and possibly be responsible for killing the deal if it imposes restrictions beyond what was agreed on in negotiations.

Daryl G. Kimball, head of the Arms Control Association and a supporter of the agreement, said the IAEA's latest report confirms that the deal is blocking Iran's path to a nuclear bomb.

“President Trump should recognize and support what our European allies have said,” Kimball said, “that we can build upon key elements of the Iran nuclear deal in the years ahead, but only if all sides fully implement their existing obligations, and that the United States cannot unilaterally ‘renegotiate’ the terms of this multilateral agreement.”

But Mark Dubowitz, the head of the Foundation for Defense of Democracies and a strong critic of the agreement, said the basic flaw is that the accord does not guarantee that Iran will not eventually be capable of developing nuclear weapons.

“The problem with the nuclear deal is not whether Iran is complying or cheating,” he said. “It is the dangerous reality that the very structure of the deal gives Iran patient pathways to nuclear weapons and [intercontinental ballistic missiles] simply by following the deal and waiting patiently for key restrictions to sunset.”