The Japanese invaded Brunei on 16 December 1941, eight days after their attack on Pearl Harbor and the United States Navy. They landed 10,000 troops of the Kawaguchi Detachment from Cam Ranh Bay at Kuala Belait. After six days' fighting, they occupied the entire country. The only Allied troops in the area were the 2nd Battalion of the 15th Punjab Regiment based at Kuching, Sarawak.