Pearl Harbor. However, it is debatable whether the US government actually knew it was going to happen. That's the short answer anyway.
The naval battle of Midway was deemed to be the turning point of the war with Japan. The American's catching the Japanese Aircraft carriers unprepared was a surprise attack in many ways.
The Japanese had planned a surprise attack on Midway. The surprise was foiled because the US had broken Japan's military code and the US was prepared for the attack.
It brought about the entry of the US into WW2, and the defeat and surrender of Japan.
umm Japan
it was a surprise from japan that they were not expecting
WWII began between the US and Japan with the surprise attack on the US Fleet at Pearl Harbor.
The Japanese had planned a surprise attack on Midway. The surprise was foiled because the US had broken Japan's military code and the US was prepared for the attack.
Hawaii
It brought about the entry of the US into WW2, and the defeat and surrender of Japan.
Eventually they did, after Japan had executed a devastating surprise attack on Pearl Harbor.
Japan.
umm Japan
East Asia. Manchuria
it was a surprise from japan that they were not expecting
On December 7, 1941, Japan launched a surprise attack on Pearl Harbor. The attack occurred in two separate waves. At the end of the attack, all 8 US battleships there were either sunk/severely damaged. Over 2,400 American sailors were killed in the surprise attack.
WWII began between the US and Japan with the surprise attack on the US Fleet at Pearl Harbor.
The surprise Japanese attack on Pearl Harbor on December 7, 1941, led to the US declaring war on Imperial Japan. As a result of this, Hitler declared war on the US. This placed the US in a two front war against Japan and its Axis powers of Germany and Italy.
On December 7, 1941, Japan launched a surprise attack on Pearl Harbor. The attack occurred in two separate waves. At the end of the attack, all 8 US battleships there were either sunk/severely damaged. Over 2,400 American sailors were killed in the surprise attack.