Battle Beneath the Earth

A Chinese general goes berserk and has a system of tunnels dug all the way from China to USA, under the Pacific Ocean. The man who has discovered this is locked up because they think he is insane. US Navy soldiers go underground to repel the invaders.

Battle Beneath the Earth is a 1968 thriller sci-fi movie directed by Montgomery Tully, starring Peter Arne, Robert Ayres, Kerwin Mathews. It holds an IMDb rating of 4.6/10 from 1,087 votes and runs 1h 31m.