Iran is seeking to expand its supply of advanced weapons to Russia, the head of Israel’s Mossad spy agency said Thursday, according to local media.

The warning from David Barnea came after the United States expressed alarm this month over a “full-scale defense partnership” between Tehran and Moscow, which invaded Ukraine last February.

In November, Tehran admitted it had sent drones to Russia but insisted they were supplied before the invasion.

“We warn against Iran’s future intentions, which they are trying to keep secret, to deepen and expand the supply of advanced weapons to Russia, to expand the uranium enrichment project and to intensify their attacks against friendly Muslim countries in the region,” Barnea was quoted as saying during a ceremony for the Jewish Hanukkah holiday.

In late October, Israeli President Isaac Herzog indicated that he had shared with Washington information that, according to Israeli intelligence, showed the use of Iranian drones in the Ukraine war.

On December 9, Washington described an extensive relationship between Iran and Russia involving equipment such as helicopters and fighter jets as well as drones, with the latter items resulting in new U.S. sanctions.

Moscow’s U.N. envoy Vassily Nebenzia responded at the Security Council that Russia’s military industrial complex “doesn’t need anyone’s assistance” and said the drone allegations had been refuted multiple times.

Last week, British Foreign Secretary James Cleverly said the Tehran regime, which has seen more than three months of civilian protests, was “striking sordid deals” with Moscow “in a desperate attempt to survive.”

Iranian-manufactured drones supplied to Russia have played a central role in attacks on civilian targets in Ukraine, Britain’s Foreign Commonwealth and Development Office said.

Iran’s Foreign Ministry on Sunday said in a statement it would not “seek permission from anyone” to expand relations with Russia.

“Cooperation between Iran and Russia in various fields including defense is expanding within the framework of common interests … and is not against any third country,” Foreign Ministry spokesman Nasser Kanani said.

Iran and Israel have for years engaged in a shadow war. Israel accuses Iran of seeking to acquire a nuclear weapon, which Tehran denies.