The US always 'negotiated' from a position of superiority.
Do tell me, which side has the superiority in force according to the following figures which were the relative strengths in December 1941:
Aircraft carriers: Japan, 12; United States, 8 (only 3 of which were in the Pacific)
Naval aircraft: Japan, 672; United States, 671 (only 280 of which were in the Pacific)
Battleships: Japan, 11; United States, 17 (only 9 of which were in the Pacific)
Heavy cruisers: Japan, 18; United States, 18 (13 of which were in the Pacific)
Light cruisers: Japan, 17; United States, 19 (11 of which were in the Pacific)
Destroyers: Japan, 104; United States, 183 (only 80 of which were in the Pacific)
Submarines: Japan, 67; United States, 112 (73 of which were in the Pacific)
Army and Marine divisions: Japan, 51; United States, 30 (only 4 of which were in the Pacific)
In terms of the force available in the theatre at the outbreak of the war, it's clearly in Japan's favour. Even when comparing to the total U.S. strength Japan is very competitive. What Japan didn't have was the ability to wage a long war. It had built a first-rate naval force, but it was strictly a second-rate power in industrial terms. Hence Yamamoto's insistence on a first strike at Pearl Harbor to put the U.S. Pacific Fleet out of action giving his forces free reign to achieve their objectives. Once gained, it was hoped the Japanese could build and hold a defensive perimeter that the U.S. would not be able to break, or would be too costly to successfully break.
Japan seriously underestimated the economic juggernaut against which they were going to war, just as Germany seriously underestimated the fighting strength of Russia. (It didn't help that Japan's own military doctrine and practices unintentionally aided the Allied war effort. For example, their best naval officers often choose to go down with their ships; they never considered the Allied merchant fleet a worthy military target; and they were slow to recognize that defence is at least as important as offence in terms of fighter aircraft design.)