Could Stalin strike the Japanese home islands?

Could Stalin attack the Japanese home islands while major Japanese ships were serving in Europe?

No credible naval invasion was available, and only part of Japan's fleet would have left home waters.

The expeditionary force is only part of the Imperial Japanese Navy: Ryūjō and numerous other ships remain in the Pacific. The Soviet Union has no Far Eastern fleet capable of mounting the proposed assault. Bomber attacks are theoretically possible, but they would still face the bulk of Japanese air and naval defences.