On 12 December 1941, I-10 was reassigned to the Advance Force, and that day she received orders to proceed to the United States West Coast and patrol in an area off San Diego, California. On 13 December 1941, Japanese Imperial General Headquarters ordered the submarines of the 6th Fleet to bombard the U.S. West Coast. On 14 December 1941, the 6th Fleet′s commander, Vice Admiral Mitsumi Shimizu, in turn ordered I-10 and the submarines , I-15, I-17, , , , I-25, and each to fire 30 rounds at targets on the U.S. West Coast on the evening of 25 December 1941, with the commander of Submarine Squadron 1, Rear Admiral Tsutomu Sato. aboard I-9 in overall command of the bombardment. On 22 December 1941 the commander-in-chief of the Combined Fleet, Admiral Isoroku Yamamoto, postponed the bombardment until 27 December. On 27 December 1941, Sato cancelled the bombardment because most of the submarines tasked with carrying it out were low on fuel. I-10′s time off the U.S. West Coast otherwise passed quietly. On 9 January 1942 she was reassigned directly to 6th Fleet headquarters, and on 11 January 1942 she arrived at Kwajalein.
