The Trump administration announced Friday that it is slapping new sanctions on more than two dozen Iranian individuals involved in the country’s nuclear and missile research programs, as Secretary of State Mike Pompeo denounced Iran’s growing influence.

The Treasury Department said the sanctions target 31 Iranian scientists, technicians and companies affiliated with Iran’s Organization for Defense Innovation and Research, which is known to have been at the forefront of Iran’s nuclear weapons program.

“Individuals working for Iran’s proliferation-related programs—including scientists, procurement agents, and technical experts—should be aware of the reputational and financial risk they expose themselves to by working for Iran’s nuclear program,” the State Department said in a statement on Friday.

The administration’s move to impose sanctions is unusual, because they are not focused on what the individuals are currently doing, but rather because of their past work in nuclear weapons development, and the potential that they could attempt to restart the nuclear activities.

The officials targeted continue to work in Iran’s defense sector and are part of a core group of experts who could reinstate the nuclear program. The sanctions cover 14 people, including the head of the organization, and 17 subsidiary operations.

The sanctions freeze assets that those targeted may have in the U.S., and bar any Americans from any transactions with them. Officials said the move will make those targeted “radioactive internationally,” and would make anyone who does business with them subject to further U.S. sanctions.

Iran pledged not to continue work on atomic weapons under the 2015 nuclear deal. The United Nations’ nuclear watchdog has said that Iran continues to comply with that agreement, which the U.S. pulled out of last year, calling it fatally flawed.

The Trump administration has re-imposed U.S. sanctions that were eased under the terms of the agreement, and it continuing to impose new ones as part of a pressure campaign to force Iran to agree to renegotiate the agreement.

The announcement came as Pompeo was in Beirut warning Lebanese officials to curb the influence of the Iran-backed Hezbollah movement. He says Hezbollah is a terrorist organization and should not be allowed to set policies or wield power despite its presence in Lebanon's parliament and government.

The Associated Press contributed to this report.