J1 amphib to Alaska/W. Can is right out. The Japs just can’t afford it, they must land infantry in Asia.
But J2 landing in Alaska/WCan is POTENTIALLY sound against a KGF, because the US should be concentrating on grinding out that early game.
I sometimes harass Alaska/W. Can as a target of opportunity, using batleship support shot(s) and a fighter that lands on a carrier. But that’s rare because a UK bomber near the Asian coast can blow up Jap transports . . . I remember I played against a Japan player once that didn’t guard his transports, and I killled three transports with one bomber (wipes nostalgic tear). But against good US players, I usually leave Alaska alone until J3-J4, then pull light harassment.
J3-J5 you have lots of Japanese transports, and you threaten a major landing at W. Canada, forcing the US to either make a defensive build or PREPARE for a defensive build. Right when Japanese units are at Moscow’s door, more infantry to the Asian coast doesn’t help, and that’s when you start messing with the US in force.