KIEV, Ukraine (AP) — Ukraine's acting president says a top air force commander is being held after his base in Crimea was stormed by pro-Russian forces and is calling for his release.

Ukraine's leader says the commander of the Belbek Air Force base near Sevastopol was "abducted." It was unclear if the forces, who didn't bear insignia, were Russian military or local pro-Russia militia.

Russia formally annexed the Crimean Peninsula, which is home to Russia's Black Sea Fleet.