U.S. President Donald Trump’s war against Iran could use up stocks of air defense missiles crucial for defending Ukraine against Russian attacks, Ukrainian President Volodymyr Zelenskyy has warned.

U.S.-made Patriot interceptor missiles are seen as vital to shooting down Russian rocket attacks and have been highly prized by Ukraine in its four-year long defense against Kremlin chief Vladimir Putin’s invading forces.

But European officials, speaking anonymously because the matter is sensitive, raised concerns that the American and Israeli war on Iran will see U.S. forces burn through their stocks of Patriots to protect themselves against Iranian attacks, leaving fewer available for Ukraine.

While there is no sign so far of stocks running out, if the conflict in the Middle East drags on it “will certainly affect supplies,” Zelenskyy told reporters in a WhatsApp group message on Monday.

“So far, everything is going as it was, but of course we know that a long war, if it is long, and the intensity of hostilities will affect the number of air defenses for us,” he said.

“Everyone understands that for us this [air defense missiles] is our life.” Zelenskyy added.