President Trump threatened sanctions after backing off military action.

Secretary of State Mike Pompeo and Treasury Secretary Steve Mnuchin detailed new sanctions on Iran at the White House Friday morning — the response President Donald Trump chose after backing away from further military conflict after Iran fired missiles at U.S. forces following his order to kill Iran’s top commander, Qassem Soleimani.

Mnuchin said the administration was committed “to stop the Iranian regime’s global terrorist activities.”

Pompeo said the sanctions target eight senior Iranian officials and were designed, as he put it, “to strike at the heart of Iran’s internal security apparatus.”

He said the sanctions would hit “other leaders close to the ayatollah” and would “deny the regime the resources to carry out its destructive foreign policy,” saying they would cost Iran “billions in revenue.”

On Wednesday, when delivering his much-anticipated remarks on how he would react, Trump said, “As we continue to evaluate options in response to Iranian aggression, the United States will immediately impose additional punishing economic sanctions on the Iranian regime. These powerful sanctions will remain until Iran changes its behavior.”

“Immediately,” he said Thursday when asked when U.S. sanctions on Iran would go into place. “It’s already been done. We’ve increased them. They were very severe, but now it’s increased substantially.”

While Iran is already under heavy U.S. sanctions, the White House could order more individuals, businesses and government agencies to be designated, according to analysts. Last May, Trump authorized sanctions on Iranian iron, steel, aluminum and copper sectors, which the White House said comprise 10 percent of Iran’s export economy, but those have so far not been used.

“Sanctions now touch every part of the Iranian economy and are unlikely to have any further impact,” Ryan Fayhee, a former senior Justice Department prosecutor who handled sanctions cases, told ABC News, suggesting instead that only secondary sanctions — targeting foreign businesses from Russia or China, for example — would have additional impact now.

ABC News’ Conor Finnegan contributed to this report.