European officials warned Iran on Wednesday that it has yet to take the necessary steps to prevent the reinstatement of United Nations sanctions over its nuclear program.

The warning followed a call between Iran and representatives of France, Germany, the United Kingdom, along with EU foreign policy chief Kaja Kallas.

“The window for finding a diplomatic solution on Iran’s nuclear issue is closing really fast,” Kallas said in a statement. “Iran must take credible steps to meet the demands of France, the U.K. and Germany. That means full cooperation with the International Atomic Energy Agency and allowing immediate inspections at all nuclear sites.”

Germany’s Foreign Ministry echoed the concern on X, writing that Iran “has yet to take the reasonable and precise actions” needed to avert the return of U.N. sanctions.

Iran did not issue an immediate response, though it acknowledged earlier that the call would take place. Previously, Tehran and the IAEA had reached a deal mediated by Egypt to allow access to all Iranian nuclear sites and to provide a full account of its nuclear material. When that report will be delivered remains uncertain.

Sanctions could be reimposed through the “snapback” mechanism in Iran’s 2015 nuclear deal, which is veto-proof at the U.N. Security Council. Unless blocked, it will take effect by the end of September, freezing Iranian assets abroad, halting arms sales, and penalizing ballistic missile development.

The move is expected to further strain relations between Iran and the West, already heightened by the ongoing Israel-Hamas war and Israel’s offensive in Gaza City.