The U.S. Special Representative for Iran on Wednesday reiterated that maximum economic pressure on Iran would prevent Tehran from acquiring nuclear weapons.

“Because of our pressure, Iranian leaders have come to a decision: either negotiate with us or manage the economic collapse,” Brian Hook, U.S. Special Representative for Iran, told reporters at a State Department special briefing.​

Secretary of State Mike Pompeo earlier in the day announced his decision to end the sanctions waiver covering all remaining nuclear projects originating from the nuclear agreement with world powers.

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

The three projects covered by the waiver that has been terminated included the Arak reactor conversion, the provision of enriched uranium for the Tehran research reactor, and the export of Iran-spent and scrap research reactor fuel. The decision will take effect after a 60-day wind-down.

A waiver for Bushehr Nuclear Power Plant, however, has been extended for 90 days. "International assistance at Bushehr predates the Iran nuclear deal," Hook explained to reporters.

The United States is willing to allow fuel supply and fuel-back for the Bushehr reactor but not work on any additional units that might be constructed there, Assistant Secretary Christopher Ashley Ford who also attended the briefing said.

On Wednesday Secretary Pompeo also announced the designation of Amjad Sazgar and Majid Agha’i for supporting Iran’s proliferation of weapons of mass destruction.

Brian Hook said Sazegar managed uranium centrifuge activities that have contributed to Iran exceeding its enriched uranium stockpile in excess of its nuclear deal commitments and Agha’i has also been centrally involved in uranium enrichment centrifuge operations.

"As a result of this action today, these two individuals have been added to Treasury’s SDN list," he said.