The New York Times | Lara Jakes: The State Department announced on Wednesday that it would begin imposing economic penalties on foreign businesses working at Iranian nuclear facilities, the latest effort by the Trump administration to dismantle an Obama-era accord with Tehran.

Companies from Russia, China and Europe will have 60 days to wind down their operations converting nuclear plants for peaceful purposes, as allowed under the 2015 deal between Iran and world powers.

American officials described it as a necessary step in President Trump�s pressure campaign to keep Iran from building a nuclear weapon and to limit Tehran�s aggressions in the Middle East.

But the decision also abandons the last part of the 2015 nuclear agreement that Mr. Trump had allowed to remain in place. It no longer allows international workers to help convert reactors, and prevent production of weapons-grade fuel, nor can they keep a watchful eye on the nuclear programs to ensure Iran could not secretly violate the deal.

In a statement, Secretary of State Mike Pompeo said he could not justify extending a waiver on sanctions that permitted the companies to work at the nuclear reactors, given what he described as Iran�s �expanding proliferation sensitive activities.�

International inspectors concluded in March that Iran had amassed enough enriched uranium over the last two years to build one nuclear weapon � although it would take months, if not more, to produce a warhead that could travel long distances.

�A regime that just days ago invoked �the Final Solution� and which regularly threatens to wipe Israel off the map must never obtain a nuclear weapon,� Mr. Pompeo said in the statement. He was referring to a recent cartoon supporting Palestinian rights that was issued by the office of Iran�s supreme leader, Ayatollah Ali Khamenei, and that invoked a Nazi slogan to eradicate Jews.

The Iranian government�s �nuclear extortion will lead to increased pressure on Iran and further isolate the regime from the international community,� Mr. Pompeo said.

The United States withdrew from the nuclear accord two years ago this month. Since then, the administration has deployed a mix of diplomacy, economic sanctions and military threats to pressure Iran into negotiating a new agreement that the president and his advisers hope would go further: not only limiting its nuclear program but also curbing its ballistic missiles systems and halting support to proxy militias in Iraq, Syria, Lebanon and Yemen.

Robert Malley, who helped negotiate the nuclear agreement as a senior White House official during the Obama administration, said Wednesday�s step could backfire if Iran reverts to a more aggressive enrichment program than what would exceed the limits under the 2015 deal.

�Removing the waivers has nothing to do with tightening the noose on Iran�s nuclear program,� said Mr. Malley, now the president and chief executive of the International Crisis Group in Washington. �If anything, it�s prompting them to loosen the noose.�

But, he said, that may be precisely what the Trump administration hopes will happen: By goading Iran into violating the nuclear deal, European leaders may finally side with the United States in declaring it defunct.

�They would not view a collapse of the deal as a loss � they would view that as a gain,� Mr. Malley said of the Trump administration. He predicted the new penalties would �further frustrate the Europeans. They�ve seen the writing on the wall, that the administration is trying to undo the deal.�

The State Department�s special representative for Iran policy, Brian H. Hook, declined to detail discussions with European officials on the issue and maintained that the 2015 accord �did not moderate the regime�s behavior.�

In a briefing to reporters Wednesday evening, State Department officials played down any security risks that might result from effectively prohibiting international workers from acting as watchdogs at the Iranian nuclear sites.

Christopher Ford, an acting assistant secretary of state, called that a �quite negligible� risk. He said the United States would continue to insist that International Atomic Energy Agency inspectors had access to the sites � what he described as a far more critical level of oversight.

Work on the nuclear facilities that were the focus of Wednesday�s announcement included converting the heavy-water reactor at Arak, allowing uranium enrichment at a research reactor in Tehran and exporting the reactors� spent and scrap fuel.

However, the State Department extended a 90-day waiver for work at the Russian-built Bushehr nuclear power plant to ensure what officials said were valid safety of operations.

The State Department also accused two officials at the Iranian Atomic Energy Organization of contributing to the proliferation of weapons of mass destruction for their work on centrifuge systems that enrich uranium � the fuel needed to make a weapon. That designation seeks to freeze the financial assets of the two officials, Majid Agha�i and Amjad Sazgar.

David E. Sanger contributed reporting.