The fleets moved on radio silence.
Whey were detected but they thought the Japanese were a group of b-25s from California
Radio silence.
Japanese
The Japanese needed to neutralize the US by attacking Pearl Harbor so that they could expand Japanese interests in the Pacific .
Short answer: Pearl Harbor attacks by the Japanese
After the attack on Pearl Harbor, the Japanese attacked various locations in the Pacific, including the Philippines, Guam, Wake Island, and Hong Kong.
Japan wanted US out of the out Pacific
They bombed pearl harbor
The Japanese Imperial Fleet attacked the US Pacific Fleet at Pearl Harbor.
The war in the Pacific was precipitated by a Japanese attack upon Pearl harbor . The Japanese sought to expand their empire by crippling US forces assigned to the Pacific for military duty .
The port at Pearl Harbor gave the U.S. a power point in the Pacific. One of the primary goals of the Japanese was to control the Pacific. With that in mind U.S. control anywhere west had to be removed.
USS Ward detected the first Japanese periscope before the attack on Pearl Harbor on December 7, 1941.