what action broke off us negotiations with japan?\njapans war with china\njapans invasion of…

Brief Explanations:

Japan's invasion of Indochina in 1940 - 1941 was a significant escalation in its expansionist policies in Southeast Asia. This action was seen as a threat to American interests in the region and led to the breakdown of negotiations between the US and Japan. The US imposed sanctions and embargoes in response, which further strained relations and eventually led to the attack on Pearl Harbor. Japan's war with China had been ongoing for years and did not directly break - off negotiations. The pact with Germany and Italy was a political alliance but not the immediate cause of the breakdown. There was no significant "pact with Indochina" that led to this.

Answer:

Japan's invasion of Indochina