I find this exactly the strategic dilemma for Japan!
Japan strengthens its position when DOW J2 but that may weaken the German/Italian positions. Some US players are even ready to go for Gibraltar and start projecting a threat into Europe in US 2 .
If UK DOWs UK2 as general play, it may just end up strengthening both axis nations. But I can see it working in some cases, especially if the German threat levels are low in Europe and Japan is out of position with its fleet.