Germany and the Soviet Union attack Japan in 1941

What if Germany and the Soviet Union jointly attacked Japan instead of launching Barbarossa in June 1941?

Japan likely allies with Britain, its fleet transforms the Mediterranean balance, and the Axis-Soviet coalition has no practical naval answer.

Germany and the Soviet Union would have little practical means of attacking Japan at sea, while their declaration of war makes Japan a plausible British ally. Japanese ships and aircraft could reinforce the Mediterranean against Italy and then help Britain in the North Atlantic. A German or Soviet fleet sailing east would first have to pass British-controlled approaches. The United States might join because it would not want Britain and Japan to determine the postwar order without it. The coalition also has a political weakness: Nazism remains hostile to communism, so a German-Soviet alliance against Japan could fracture even during the war. By then, both states could already be fighting a powerful maritime coalition.