The timing of Mr. Sullivan’s comments about what presumably had been classified intelligence was also curious, coming almost as an aside at the end of a briefing to preview President Biden’s trip this week to Israel and Saudi Arabia, where Iran’s nuclear program and malign activities in the region will be a key subject of discussion.
Iran has supplied drone and missile technology to Houthi rebels in Yemen, who have attacked Saudi Arabia and the United Arab Emirates, as well as to Shia militia in Iraq, who have carried out drone strikes against U.S. troops there. But Mr. Sullivan’s comments about any imminent transfer of Iranian drones to Russia to use in Ukraine caught several senior U.S. national security officials by surprise on Monday.
The Biden administration is trying to slow Russian weapon manufacturing by denying it components made with Western technology. Gina M. Raimondo, the commerce secretary, said last month that American and international controls had lowered exports to Russia of semiconductors and computer chips by 90 percent.