How did U.S. forces attack Japanese cave defenses on Okinawa?

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U.S. Marines on Okinawa — Battle of Okinawa U.S. Marines battling for control of a ridge near Naha, Okinawa, May 1945.

During the Battle of Okinawa, U.S. forces faced significant challenges overcoming Japanese cave defenses, which provided effective shelter against heavy bombardment. Because these positions were so well-fortified, American troops were forced to destroy each cave and fortification individually in a process that was both dangerous and costly.1

To neutralize these defenses, U.S. forces employed the following tactics:

Flame-throwing tanks: These vehicles led infantrymen in assaults against the caves, using fire to clear the positions.1
Explosives: Ground troops utilized dynamite charges to seal the numerous entrances to the underground networks.1
Close-quarter combat: Because long-range artillery and aerial bombardment were often futile against the subterranean fortifications, infantry had to engage in savage, close-quarters fighting to secure the areas.1

This methodical approach was necessary because the Japanese defenders, who fought with extreme tenacity, had created complex underground systems—such as those at "Chocolate Drop Hill," which featured hundreds of individual openings—that required manual destruction.1