The United Kingdom, France, and Germany have agreed to reimpose tough United Nations sanctions on Iran by the end of August if no tangible progress is made on reviving a nuclear deal, according to two European diplomats.

Ambassadors from the three countries met at Germany’s U.N. Mission on Tuesday to discuss the matter. The issue was also raised in a phone call Monday between U.S. Secretary of State Marco Rubio and the foreign ministers of the three European nations, U.S. officials said.

Following the call, the State Department said the parties discussed “ensuring Iran does not develop or obtain a nuclear weapon.”

The U.K., France, and Germany are parties to the 2015 nuclear agreement with Iran. The deal, from which U.S. President Donald Trump withdrew during his first term, offered sanctions relief in return for restrictions and monitoring of Iran’s nuclear program. The deal includes a “snapback” provision allowing the reimposition of U.N. sanctions if Iran fails to comply.

UN rapporteur urges global action to stop ‘Genocide’ in Gaza

French Foreign Minister Jean-Noel Barrot told reporters in Brussels that the three nations would be justified in reapplying sanctions. “Without a firm, tangible, and verifiable commitment from Iran, we will do so by the end of August at the latest,” he said, according to Reuters.

Iranian Foreign Minister Abbas Araghchi said Tehran would resume nuclear talks if there were guarantees against future attacks on its nuclear sites, citing Israeli and U.S. strikes. President Masoud Pezeshkian said recent U.S. airstrikes severely damaged facilities, leading Iran to suspend cooperation with the IAEA.

Iran’s U.N. Mission declined to comment.