Battle Beneath the Earth (1968)

In this rabid anti-communist science fiction tract, scientist Arnold Kramer (Peter Arne) convinces the Pentagon that the communist Chinese are digging a complex series of tunnels from China and beneath the United States, from which they plan to detonate nuclear weapons and destroy the free world. Kramer enlists Commander Jonathan Shaw (Kerwin Mathews) to assist Kramer in trying to prevent the literal and final collapse of the U.S.A. Shaw sets up shop inside an extinct Hawaiian volcano, attempting to destroy the main supply tunnel coming from China. But before the team can complete their mission, they are captured y the evil Chinese. Now it is up to Shaw and Kramer to escape the clutches of the Chinese in order to activate a nuclear stockpile inside the tunnel and incinerate the Chinese forces. ~ Paul Brenner, Rovi