Attributing Japan's imperialist ambitions to a desire to emulate the west is quite a stretch. I don't believe any historian has made this argument. Your argument seems to follow that the US ought to have left China, Korea, & SE Asia to suffer the brutality of Japanese occupation while continuing to supply Japan with the materials necessary to continue making war on them.
That would not have been honorable. I don't see how FDR's Day of Infamy speech was a lie. It's true the US government expected war with Japan. Once oil & steel had been embargoed Japan's choices were scale back their empire or go to war. But no one expected them to steam thousands of miles across the Pacific to attack Pearl Harbor. That was an outrageous risk. The only similar action was the Royal Navy's attack on the Italian fleet at Taranto. But that was in the Mediterranean, which the British controlled. In fact the attack wasn't a complete success because, not finding US carriers in port, Nagumo called off the third wave, which was intended to destroy the fueling depots & make Pearl unusable. He feared the kind of ambush that would take place a few months later at Midway.
Of course no one expects a nation to announce its war strategy ahead of time, but that the attack took place before war had been officially declared made it seem treacherous.
I agree that the atomic bombing was unnecessary. And in fact far more leaders than just Eisenhower & Leahy opposed it. Problem for historians is that many of the Allied leaders who opposed it prior, changed their tunes after it became a fait accompli. Was it especially barbarous? Compared to the fire bombings of Tokyo, Dresden & Hamburg? I'm not so sure. At least not at the time. I think it was seen as another, especially effective weapon of war. In particular the lingering effects of radiation weren't well understood. But certainly its use was a tragedy. Had Truman agreed to guarantee the Emperor's safety & continuance on the throne the Japanese would have surrendered. Of course the irony is that is exactly what we did.
