President Trump will slap sanctions on Europeans and other allies who resist the U.S. effort to isolate Iran’s economy, Secretary of State Mike Pompeo said Monday.

“We will hold those doing prohibited business in Iran to account,” Pompeo emphasized during a speech at the Heritage Foundation. “I've spent a great deal of time with our allies in my first three weeks. I know that they may decide to keep their old nuclear deal going with Iran. That is certainly their decision to make. They know where we stand.”

Leading western European powers are working to convince Iran to remain in the 2015 nuclear deal, which they believe has defused a regional nuclear crisis. The European Commission has moved to protect companies from American sanctions in order to ensure that the regime reaps the economic benefits of the pact. But Pompeo reiterated that such efforts wouldn’t prevent the United States from implementing an “unprecedented” effort to bring Iran to its knees through sanctions.

“Anytime sanctions are put in place, countries have to give up economic activity,” he replied when asked if the State Department would try to soften the blow for European allies. “Every country is going to have to understand that we cannot continue to create wealth for [Iranian general] Qassem Soleimani. That's what this is about. At the end of the day, this money has flowed to him. ... Our effort is to strangle his economic capacity to do harm to the Middle East and to the world.”

European allies worry that Iran will carry out threats to jump-start its nuclear program, renewing a crisis in the Middle East analogous to North Korea’s flurry of nuclear weapons and ballistic missile tests. Pompeo warned Iran against doing so.

“Should they choose to go back, should they begin to enrich, we’re fully prepared to respond to that as well,” he said. “I’m certainly not going to share with you today precisely what our response will be. But we watched them talk, we’ve heard them say [that]. I hope that they’ll make a different decision, that they’ll choose a different path.”

U.S allies in the 2015 deal, by contrast, want to avoid that by trying to provide legal protection and financing to European businesses that invest in Iran. “The European Union is committed to mitigating the impact of US sanctions on European businesses and taking steps to maintain the growth of trade and economic relations between the EU and Iran that began when sanctions were lifted,” the European Commission said Friday.

Europe has a limited ability to interfere with American sanctions, however, because the largest corporations investing in the country have major U.S. operations and thus can’t afford to provoke the Treasury Department. Additionally, Pompeo argued that the sanctions would amount to a newly-effective cap on the regime’s nuclear program.

“Nuclear programs aren't cheap,” he said. “To the extent we are effective at making it more difficult on the Iranian regime, we will reduce the capacity to continue to build out their nuclear weapons system as well.”