The United States has not seen evidence that Iran has transferred ballistic missiles to Russia for use against Ukraine, the White House said on Wednesday.

John Kirby, spokesperson for the White House National Security Council, told reporters the United States has seen the continued provision of Iranian drones to Russia.

“We know that their defense industrial base is being taxed,” Kirby said of Russia. “We know they’re having trouble keeping up with that pace. We know that he’s (Russian President Vladimir Putin’s) having trouble replenishing specifically precision guided munitions.”