Crimea said on Tuesday that long-range Army Tactical Missile Systems (ATACMS) were shot down over the peninsula, which was annexed by Russia in 2014.
Sergei Aksyonov posted on Telegram a photo showing what he described as undetonated submunitions of ATACMS missiles.
Aksyonov did not specify when and how many missiles had been shot down.
The United States in recent weeks secretly shipped long-range missiles to Ukraine, which has so far used them twice, a U.S. official said last week.