The crash site
On April 18, 1943 United States Army Air Corp P-38 Lightening's,operating out of Kukum Field on Guadalcanal intercepted two Japanese G4M "Betty" bombers and shot them down on the Bougainville coast. The action is notable as it intentionally and successfully targeted Japanese Admiral Isoroku Yamamoto, who died of woulds before the planes crashed to earth. The American action was a remarkable tactical success in that the distances and time involved made such an action more likely to fail that succeed. It was only possible in the first instance as the US was intercepting, famously, Japanese encoded message and, because of that, the mission was risky in that it risked alerting the Japanese to that fact. To cover up that aspect of it, the US created a fictional story of coast watchers having seen the plans and the action simply being fortuitous. Amazingly, the Japanese seem to have been convinced by that questionable deception.
But did it do any good?
The US got Yamamoto as he was know to be the central figure of the planning of the attack on Pearl Harbor. He was a major and celebrated Japanese military figure in Japan, but we now know that he was not terribly enthusiastic about fighting the United States. It's not clear that he opposed it either, contrary to the sometime popular view.
His death deprived Japan of Yamamoto, to be sure. Maybe it deprived the US of him too as it is clear, now, in retrospect, that Japan couldn't have won the war. Maybe it meant that brilliant planning he would have done in defensive campaigns in the Pacific would now not occur. . . or maybe it meant that a voice that was familiar with the United States and the American mind was now silenced. It's known that Yamamoto feared what getting into a war with the US would mean, although its not really clear if he uttered the words attributed to him following Pearl Harbor, "I fear we have awoken a sleeping giant and filled him with a terrible resolve.".
Maybe his death made no real difference in the progress of the war at all.
I note all of this as the historically minded are now looking this event up to draw conclusions from it. Maybe it offers no real comparisons with the just occurred strike on an Iranian general in Baghdad. The killing on Yamamoto was tactical and strategic, but it also had an element of revenge to it and of propaganda to it, as had the earlier Doolittle Raid. The killing of Qasem Soleimani was more of a strategic decapitation.
Both events are extraordinary. Yamamoto was the only senior officer in World War Two that I'm aware of that was the specific target of a mission. Such an action is not an illegitimate act of war, but it's a risky one. In taking on Japan in that fashion, the US was targeting an enemy that lacked the capacity to reply and, although largely unknown to us at that time, was in the progress of starving senior officers that it held in captivity. Nobody attempted any such actions against senior German military figures except, as it would turn out, the German army, unsuccessfully, itself. We were vulnerable in the west to a counterattack.
Just all things to consider.