Xtro 3: Watch the Skies

For years, the government has successfully covered up very real proof of U.F.O.s. but when a group of Marines is dispatched to a deserted island, they uncover unsettling evidence: old films documenting brutal medical experiments on aliens. They also uncover a lone surviving alien out for revenge, and a military intelligence plot to sacrifice them and conceal existence of the encounter. The shroud of mystery is about to be lifted. (official distributor synopsis)