The United States announced on Friday that it will tighten restrictions on Iran's nuclear program as part of the administration’s "unprecedented maximum pressure campaign" to address the full range of Tehran's activities.

"The Trump administration continues to hold the Iranian regime accountable for activities that threaten the region’s stability and harm the Iranian people. This includes denying Iran any pathway to a nuclear weapon," read a statement issued by the State Department.

"Starting May 4, assistance to expand Iran’s Bushehr Nuclear Power Plant beyond the existing reactor unit could be sanctionable," it announced. "In addition, activities to transfer enriched uranium out of Iran in exchange for natural uranium could be sanctionable."

The U.S. State Department stressed that Iran must stop all proliferation-sensitive activities, including uranium enrichment, affirming that Washington will not accept actions that support the continuation of such enrichment.

"We will also no longer permit the storage for Iran of heavy water it has produced in excess of current limits; any such heavy water must no longer be available to Iran in any fashion."

The statement pointed out that Secretary Mike Pompeo took steps to permit the continuation of projects that help restrict Iran’s ability to reconstitute its past nuclear weapons program.

"Our policy preserves oversight of Iran’s civil nuclear program, reduces proliferation risks, constrains Iran’s ability to shorten its breakout time to a nuclear weapon, and prevents the regime from reconstituting sites for proliferation-sensitive purposes."

"We reserve the right to revoke or modify our policy covering these nonproliferation activities at any time if Iran violates its nuclear obligations or commitments or we conclude that such projects no longer provide value in constraining Iranian nuclear activities," the statement said.

"The United States will continue to impose maximum pressure on the Iranian regime, and remains committed to denying Iran any pathway to a nuclear weapon," it concluded.