Political map of the Arctic & the Far North 07 December 1941 (Attack on Pearl Harbor): By late 1941, the still neutral United States was firmly behind the Allied (Allies of World War II) war effort and even allowing US destroyers to escort British ships and hunt German submarines in the hugely extended Pan-American Security Zone. Meanwhile, in the Pacific, US relations with Japan were being strained by the ongoing Japanese war in China (Second Sino-Japanese War). On December 7, frustrated by a US embargo (Events leading to the attack on Pearl Harbor), the Japanese launched a surprise attack on the US Pacific Fleet at Pearl Harbor (Attack on Pearl Harbor), bringing America suddenly into the War (World War II).