4 years
China did not attack Pearl Harbor, Japan did.
get your own answer
Japans willingness to adopt more of china's culture
They were at war with China
China. Japan invaded China in 1937.
Japan was at war in China and signed the Tripartite Pact with Germany.
Japan's invasion of China and the Panay Incident.
China could not fight Japan.
The US fleet was at Pearl harbor, contrary to the opinion that Japan attacked the US unprovoked. The US and Britain were fighting Japan in an undeclared war in China. Until recently declared the fighters in China were Civilian volunteers.
While there were earlier attacks, such as the sinking of the gunboat Panay in China, the first full scale attack on US Forces was at Pearl Harbor, Hawaii on 7 Dec 1941.
The Japaneses attacked Peal harbor because they attacked China and we the USA did not want China being targeted for we imported so much from them. So the USA cut off Japan from supplies
Japan's first act of open aggression happened on 1871. Okinawa was being claimed by China, which caused Japan to attack Taiwan.