Since the U.S. withdrawal and the revival of American sanctions to cut Iran's oil exports, Tehran has boosted its nuclear work in what analysts see as an effort to change United States policy or increase Iranian leverage in any negotiation.

The United Nations Security Council has argued the JCPOA was necessary to ensure nuclear nonproliferation in Iran and to stabilize the region as a whole.

Kelsey Davenport, director for nonproliferation with policy at the Arms Control Association, wrote in a tweet, "Ending waivers for cooperative projects jeopardizes U.S. nonproliferation priorities & hands Iran a justification to ratchet up certain nuclear activities limited by the #IranDeal".

"The Iranian regime has continued its nuclear brinkmanship by expanding proliferation-sensitive activities", Pompeo said in a statement that pointed out that Iran has admitted to activities that are in violation of the deal.

The waivers provided by the USA relate to projects at Iran's Arak heavy water research reactor, regulation of enriched uranium at the Tehran Research Reactor and the disposal of spent and scrap research reactor fuel out of Iran, the Post reported.

Deal supporters say the waivers give worldwide experts a valuable window into Iran's atomic program that might otherwise not exist.

The Trump administration is expected to renew a separate waiver for the Bushehr nuclear power plant, the Post reported, to "help ensure the safety of operations at the plant", according to the internal memo obtained by the paper.

"We are taking these actions now because the regime continues to use its nuclear program to extort the global community", Hook told reporters and added: "The Iranian regime's threats are created to intimidate nations into accepting Iran's usual violent behavior for fear of something worse".

But the administration believed Iran was ramping up its nuclear proliferation efforts.

"We are going to make sure that come October of this year, the Iranians aren't able to buy conventional weapons that they would be given what President Obama and Vice President Biden delivered to the world in that awful deal", the secretary said in a briefing with reporters at the time.

The justification is seen as setting up the chance for the U.S.to call for a snapback on all sanctions on Tehran, and Pompeo said last month the USA doesn't "have to declare ourselves a participant".

Goldberg added that Bushehr "was not in any way connected to a nuclear-weapons capability. It is a nuclear power plant that can produce nuclear energy for peaceful purposes" and that the facility can't "be decommissioned overnight".

The Trump administration in the past had tacitly acknowledged benefits from letting other nations continue the nuclear deal. It no longer considers itself bound by any of its commitments.

The nuclear deal also required modifications to the Arak reactor to block Iran's pathway to nuclear weapons using plutonium.

Pompeo said that the United States was issuing a final 60-day waiver to allow companies involved in the projects to wrap up operations. "So revoking remaining waivers could put an end to those projects, which serve important nonproliferation goals, and drive another nail into the JCPOA's coffin".

Sazgar is the Managing Director of the Atomic Energy Organisation of Iran entity responsible for the industrial-scale production of uranium enrichment gas centrifuge machines.

Pompeo finally went public about twenty minutes later. "The regime's vile rhetoric only strengthens the global community's resolve to counter its threats".