Why did the US keep warships in Pearl Harbor?

Answer 1

Pearl Harbor Hawaii was thousands of miles closer to Asia than the 48 states. It had a shallow harbor (which was wrongly thought to be too shallow for airdropped torpedoes. It was far away from any enemy held islands for land based planes to reach, and thought to be safe from enemy attack. There were submarine nets to prevent enemy submarines from sneaking in. There was a large Army base there as well to protect the Naval ships. In the 1920s, Gen. Billy Mitchell predicted that the Japanese would attack Pearl Harbor, (he did not say when of course), but, by December 1941, most people had forgotten about his warnings, and they did not think that the Japan could launch an air attack on Pearl Harbor with carrier planes (and torpedoes that could work in shallow water), the way the British Navy had used carrier planes to attack the Italian fleet at Taruento, Italy.

Answer 2

Pearl Harbor was a US Naval Base for the US Pacific Fleet. US warships departed & arrived at various days & times depending on their missions. The US ships in the harbor during the attack were not assigned a specific mission for that time. The battleships did not travel far from Pearl Harbor when they did depart, and did not stay out too long because there was not enough fuel oil (at Pearl Harbor) to operate the battleships & carriers at the same time. Two aircraft carriers (with cruisers & destroyers) were on missions to Wake & Midway islands. Other cruisers & destroyers were on patrol near Hawaii, and others were escorting troop convoys to & from the Philippines.