The US did not commence any military action against Japan prior to the attack on Pearl Harbor. So, your friend is incorrect. However, the American Volunteer Group, also known as the Flying Tigers, were a group of airmen that were assembled to assist Chiang's forces that was organized starting in 1940, although their first combat mission took place after December 7th 1941.

The first actual bombing of the Japanese Home Islands took place with the Doolittle Raid in April 1942.

The Japanese attack on Pearl Harbor was the end result of both rising tensions between Japan and the US over Japanese aggression in China and later Indochina, as well as 20 years of Japanese war planning and the disrupting influence of Admiral Yamamoto. Essentially, the embargo of strategic resources to Japan by the US, British, and Dutch, including oil and especially scrap metal, led to the Japanese being forced into a corner: commit political suicide (literally) by pulling out of China, or going to war to seize these resources to finish the China war. Japanese war planning was predicated on seizing these resources and building up a defense perimeter in preparation for an Allied counterattack, which the Japanese would smash and then sue for a negotiated peace. Yamamoto attempted to buy more time for this counterattack by attacking Pearl Harbor: however, it also ruined any chance of this plan succeeding as it was no longer politically feasible due to antagonizing the American populace.

Sources:

Samson, Flying Tiger: The True Story of General Claire Chennault.

Evans, Kaigun