French President Emmanuel Macron cautioned his Iranian counterpart Ebrahim Raisi on Saturday of the repercussions of sending drones to Russia, according to Macron’s office.

Macron asked Iran to “immediately cease” aiding Russia in the conflict with Ukraine during a phone call.

Macron also expressed concerns about the trajectory of the Iranian nuclear programme, the statement said.

Britain, France, Germany, the United States and Ukraine say the supply of Iranian-made drones to Russia violates a 2015 U.N. Security Council resolution enshrining the Iran nuclear deal.

The White House said on Friday that Russia appeared to be deepening its defense cooperation with Iran and had received hundreds of one-way attack drones that it is using to strike Ukraine.