What was the only part of the current United States invaded by the Japanese during WWII?

During World War II, the only part of the current United States to be invaded by Japanese forces was a remote chain of islands in Alaska. In June 1942, Imperial Japanese Army troops landed on Attu and Kiska, two islands in the Aleutian chain, marking the first time since the War of 1812 that a foreign power had occupied American soil. These attacks also included air strikes on Dutch Harbor, a U.S. naval base on Unalaska Island. The invasion shocked the American public, highlighting the vulnerability of the nation's far-flung territories.

Historians largely believe that the Japanese invasion of the Aleutian Islands served as a diversionary tactic for the larger Battle of Midway, which was launched simultaneously under the same commander, Admiral Isoroku Yamamoto. By drawing American forces northward, Japan hoped to weaken defenses in the central Pacific. Additionally, some strategists believed that controlling the Aleutians could prevent a potential U.S. attack on Japan from the north. The islands themselves were barren and characterized by rugged terrain and notoriously harsh weather, making any military operations exceptionally challenging for both sides.

The American response to this occupation began nearly a year later, culminating in the Aleutian Islands campaign, often referred to as the "Forgotten Battle" due to its overshadowed nature by other major war events. In May 1943, U.S. forces launched a fierce battle to reclaim Attu, enduring brutal fighting and extreme conditions before finally expelling the Japanese in one of the deadliest battles of the Pacific Theater. A few months later, an Allied invasion force landed on Kiska, only to discover that the Japanese had secretly withdrawn. The native Unangax (Aleut) residents of Attu were taken prisoner to Japan during the occupation, with many not surviving their internment.