Washington on Monday threatened to impose sanctions on companies or states cooperating with Iran’s drone program after recent attacks in Ukraine that allegedly used Iranian-made drones, AFP reported.

“Anyone involved in activities with Iran related to the development of drones or ballistic missiles or (involved in) the flow of arms from Iran to Russia should be vigilant,” State Department spokesman Vedant Patel said.

“The US will not hesitate to use sanctions or take measures against those most responsible. The strengthening of the alliance between Russia and Iran should be viewed by the world as a serious danger,” he added.

Citing US intelligence, the spokesman said some Iranian drones sold to Russia had malfunctioned.

Moscow’s supply from Iran was a sign of “huge pressure” on Russia after its losses in Ukraine, which was now “forced to turn to unreliable countries like Iran for supplies and equipment,” Patel said.

A week after a wave of massive strikes across the country, Russian strikes, including kamikaze drones, killed at least eight people, including four in Kyiv on Monday morning, and struck energy facilities in several regions.