The first to copy tunnel warfare were the Japanese themselves. In the battles of the Western Pacific, they would maximize their capabilities by establishing a strong point defense, using cave warfare. The first encounter of the US Marines with this new tactic was the island of Peleliu. The invading marines suffered twice as many casualties as on Tarawa, where the old Japanese tactic of defending the beach had been employed. The pinnacle of this form of defense, however, can be found on Iwo Jima, where the Japanese engineered the whole Mount Suribachi with many tunnels leading to defensive emplacements, or exits for quick counterattacks. Tunnel warfare by the Japanese forced the US Marines to adopt the "blowtorch and corkscrew" tactics to systematically flush out the Japanese defenders, one cave at a time.