Japan continued diplomatic engagement with the U.S. on several issues of concern throughout late November and into early December 1941 even though attacking ships had sailed from their base in the remote Kuril Islands. The surprise December 7, 1941 attack on Pearl Harbor took place several hours before Japan presented a formal declaration of hostilities and officially broke diplomatic ties. Japan also made extensive use of decoys and other deceptive displays throughout the war, which took on increased importance as the tide of the war went against it in 1944 and 1945.