[MRM]

No and no, Tabs. Almost right but not quite. Hitler did not declare war on the US assuming that the Japanese would declare war on Russia. He had no agreement with them, did not ask them to do that, and their treaty did not require it. Hitler was not obligated by his treaty to attack the US just because the Japanese did. No one really nows why Hitler did it other than as suggested above, he was winning and it looked like a good idea to him at the time.

The US was begging the Soviet Union to come in to the war in the Pacific for more than a year. The US was anticipating an invasion of Japan and wanted to use Soviet troops. The Soviets quite sensibly didn't see what was in it for them to get involved too early; they wanted to get involved to grab some land, but they didn't see why they had to put up any men if they could wait us out and have us do the fighting. The Soviets declared war on the Japanese almost simultaniously with the bombs being dropped so that they could get into position to grab what they could. But by then the tables turned and the US tried to keep them away because we weren't going to need their extra bodies for an invasion.

The upshot was that the Soviets got a couple of islands, didn't have to fulfill any of their promises of providing troops, and Japan was largely free of Soviet occupation after the surender.