That seems to be a pretty big theme of the books doesn't it.
No, it doesn't.
How many times have the characters talked about events that were going on in the world and how they couldn't do a damn thing about it?
Japan isn't the same category as the Russian pogroms or Armenian massacres several POV characters mentioned as being something the US cannot do a damn thing about.
Japan and the US in this time line have fought
three wars against each other; both of the world wars and the "war" which began after Japan
bombed Los Angeles. Japan was on the losing side in both world wars and was the unquestioned aggressor in the third. Japan was caught arming the Canadian rebellion and even torpedoed a US carrier as part of that effort. Yet the despite all that the US seems to have this blindspot regarding Japan about the size of Turtledove's bank account.
In the Great War, after beating the CSA and accepting the UK's request for a ceasefire, the US never redeploys to the Pacific to settle Japan's hash. Japan is able to announce it's quit fighting and keep everything it's grabbed. In the 1930s, after the US mainland in bombed by Japanese carrier planes, and despite the fact that war time spending is a great way to beat economic troubles, the US is content to dance around for a few years trading carrier raids until the war seemingly called on a lack of interest. In the 2nd Great War, after destroying the CSA, putting down a Canadian uprising, and watching it's ally Germany nuke Britain, France, and Russia several times, the US once again lets Japan off the hook and lets Japan keep her gains despite the US having nuclear weapons of it's own.
Japan is involved in these wars and Japan always avoids the consequences of those wars for one reason: Turltedove is too goddamn lazy to not to write Japan into the wars and too goddamn lazy to work out what the consequences of Japan's participation would be.
Also, does anybody know what Featherston looks like?
There are several threads on this very forum which already answered that question. One was active only a few months ago.