In the short term, the American naval presence in the Pacific was severely weakened. However, the Japanese had largely ignored the harbour’s infrastructure, and many of the damaged ships were repaired on-site and returned to duty. In addition, the Pacific Fleet’s three aircraft carriers were not present at Pearl Harbor (one had been scheduled to return the day before the attack, but it was delayed by bad weather). American opinion immediately shifted to favouring war with Japan, a course that would conclude with Japan’s unconditional surrender less than four years later.