Naval Station Pearl Harbor
The overall death toll was 2,467 people: 2,403 American citizens—2,335 members of the U.S. military and 68 civilians—and 64 members of the Imperial Japanese Navy. Five U.S. battleships were sunk and the other remaining three were badly damaged. Overall, nine ships of the U.S. fleet were sunk and 21 ships were severely damaged. Three of the 21 would be irreparable. 188 U.S. aircraft were completely destroyed and 159 others were damaged. Japan lost 29 out of the 353 aircraft they attacked with. The attack on Pearl Harbor was the largest destruction of life and property on American soil both in peacetime and in general by foreign nationals prior to the September 11 attacks, and remains the deadliest attack on American soil both in peacetime and in general by a foreign nation.
Nuclear warfare
In late June 1945, as the U.S. wrapped up the two-and-a-half-month Battle of Okinawa (which cost the lives of 260,000 people, including 150,000 civilians), it was faced with the prospect of invading the Japanese home islands in an operation codenamed Operation Downfall. Based on the U.S. casualties from the preceding island-hopping campaigns, American commanders estimated that between 50,000 and 500,000 U.S. troops would die and at least 600,000–1,000,000 others would be injured while invading the Japanese home islands. The U.S. manufacture of 500,000 Purple Hearts from the anticipated high level of casualties during the U.S. invasion of Japan gave a demonstration of how deadly and costly it would be. President Harry S. Truman realized he could not afford such a horrendous casualty rate, especially since over 400,000 American combatants had already died fighting in both the European and the Pacific theaters of the war.