More than 80 years ago, the Imperial Japanese Navy launched a devastating surprise attack on U.S. air and naval forces at Pearl Harbor.

Many Americans now believe that the attack was completely unexpected.

However, Japan began aggressive expansion around the turn of the century. As a small island, it wanted to take advantage of the natural resources of its Pacific neighbors.

The United States attempted to contain Japan’s expansion, first through diplomacy, then through sanctions, and later through embargoes. But Japan increased its military activity and relations between the two countries increasingly dissolved.

Although the United States expected war with Japan, officials did not believe that the Japanese could attack Pearl Harbor. Japan was convinced that war was inevitable and hoped to wipe out the Pacific Fleet.

How the attack happened – and what led to it