The SDF already exists and is huge. There is already a huge amount of American military across the country as well. The constitution does not prevent defensive

The SDF already exists and is huge. There is already a huge amount of American military across the country as well. The constitution does not prevent defensive measures and it is doable. What isn’t doable or is very tricky is things like Japan joining an allied nation in a fight in another place (for example it could not participate in Afghanistan or Iraq). Abe pushed for the idea of collective defense to allow for the govt to send in forces for those kinds of actions. Japan can defend itself against China all it wants, but the current legal idea is it can’t actively participate in conflicts where it’s not directly involved. This is the thing Abe wanted to change, and is an unpopular idea in Japan.