The Japanese attack force sailed from the Kurile Islands for Hawaii on November 26, eleven days prior to the Pearl Harbor strike (if you discount the 1-day shift caused by crossing the International Date Line; Nagumo’s ships were operating on Japanese time, so from their perspective the attack occurred on December 8 rather than December 7).
Asking whether Japan was going to attack “no matter what the USA tried to do for peace” seems to imply that the US might have been prepared to do anything to avoid war. Realistically, this was not the case. The diplomatic history between the US and Japan over the previous several years was a long chain of escalating problems, provocations, threats, moves and counter-moves by both sides, with each side (not surprisingly) seeing itself as the injured party. The only thing that might have stopped Japan from launching its offensive campaigns in the Asia-Pacific theater would have been if the US has reversed every political position it had taken and every sanction it had implemented with regard to Japan over the past few years. The chances of that happening in late 1941 were zero.
The main items on the list would have been for the US to give Japan a free hand in China (with which Japan had been at war since 1931 or 1933 or 1937, depending on your point of view) and for the US to unfreeze Japanese assets and to cancel its embargo on the sale of scrap metal and oil to Japan. From the US perspective, these measures were fully justified retaliations against Japan for its invasion of China and its seizure of French Indochina – Japanese actions which were totally unacceptable to the US. From the Japanese perspective, these measures were virtually a declaration of war against Japan: when the US cut off oil exports to Japan, the Japanese – who lacked domestic oil supplies – were put in a situation in which they only had about two years’ worth of oil reserves in stock. Once those reserves were used up, the Imperial Japanese Navy and Japan’s military and naval air forces would be immobilized and the Japanese Empire would have been left defenseless except for its infantry and other non-mechanized army units.
Japan therefore had two years to “use them or lose them”. “Using them” meant seizing new sources of oil in the Dutch East Indies, which meant going to war against Holland and, in practical terms, against Britain, which had several colonial possessions near the DEI. Japan also felt that this meant going to war against the US too – partly because they had a grudge to settle, partly because the US was its main competitor in the Pacific, and partly because the Philippines (a US possession) were inconveniently located on the shipping route between the DEI and Japan. Moreover, many statesmen and military officers in Japan – a notable exception being Admiral Yamamoto – had a generally contemptuous attitude towards US society in general and the US military in particular. (In fairness, various statesmen and military officers on the US side felt similarly contemptuous about Japan.) Basically, many decision-makers on the Japanese side viewed the US as a soft, decadent, undisciplined, materialistic society which lacked convictions for which it would be willing to fight, and which would fold up in short order when it was confronted by Japan’s skillful, regimented, austere, highly motivated warriors. Yamamoto knew better: he had studied at Harvard as a young man, and had served as a naval attache in Washington early in his career. He not only realized just how much economic and industrial power the Americans could mobilize if they went to war against Japan, he also understood that they would mobilize that huge warmaking potential if they ever ended up in an actual shooting war with Japan. Unfortunately, Yamamoto wasn’t calling the shots when it came to overall Japanese strategy; it was the Imperial Japanese Army which, arguably, had more of the national decision-making levers under its control at that time.
In my opinion, the only way for a war between Japan and the US to have been delayed (I don’t think it could have been avoided) and for the US war effort to have been appreciably hampered would have been if Japan had gone to war against Holland and the UK and the British Commonwealth but NOT against the US in December 1941. If Japan had been more clever, it would have left Hawaii and the Philippines and the US possessions in the central Pacific completely alone, and it would have paired its campaign against the Dutch and the British with a radio-based charm offensive in which very senior Japanese statesmen and officers would have gone on the air and asserted in mild, reasonable, dignified tones that they had nothing but friendship for the good people of America and had no designs whatsoever on their territories. This would have placed Roosevelt in an awkward position. The American isolationist lobby was very strong at the time: it had no objection to the US defending itself if it was directly attacked, but it opposed the idea of the US getting involved in the war that had been raging in Europe since 1939, and it would have opposed just as strongly the idea of the US getting into a war with Japan to protect Dutch and British colonial interests in the Asia-Pacific area.
In such a scenario, America would probably have ended up declaring war against Japan sooner or later anyway, but from the disadvantageous position of being cast in the role of the aggressor rather than as the party which had been the victim of – as Roosevelt put it – an unprovoked and dastardly attack by a treacherous enemy. This would have made the US war effort a lot harder to sell to the average American citizen than was the case historically. Japan did Roosevelt a huge favour when it hit Pearl Harbor because this attack infuriated the American public. Expressed in American terms, the attack on Pearl Harbor was – among other things – seen as a violation of the rules of fair play and good sportsmanship that Americans are taught to value from the time when they’re little kids playing sandlot baseball. Expressed in Japanese terms, the attack on Pearl Harbor was seen by the American public as a dishonorable act by Japan. It’s interesting to speculate whether anyone in Japan (like Yamamoto) who understood the Americans better than the average person ever thought of using those violation-of-honour terms to explain to the Japanese leadership why launching a surprise attack against the US might not be a great idea.
