it seems unlikely the US would want to do something like this since it would leave a big hole somewhere else for little real gain
I wholeheartedly DISAGREE Even the OPTION of doing these things is a problem. Because Japan now has to consider this new unique American ability in all of it’s moves.
On the first turn of the game, I would also bolster China, for the sole purpose of holding the Burma road - to allow builds of artillery, “cheap” infantry at 3 and artillery, will quickly prevent Japan from EVER retaking the Burma road.
The US now also no longer has to ship infantry to the mainland, and can spend instant money to secure victory cities preventing victory, without even putting ships on the board.
For the price of an aircraft carrier, I can add 5 infantry to mainland asia.
You also need to understand, that Japan HAS to match builds in mainland Asia, if they want to try and win, meaning less ships, to the less American ships.
Also please do not fail to realize, that within 2 turns America can have roughly the exact same naval power as Japan, only lacking some airforce, from a defensive position, you don’t need much more, if you intend to smash Japan elsewhere and widdle them down.
In the end… it’s all about what the US/China -can- do, irrelevant of what they -do- do. Be careful…