Hi -- I'm a bit confused on how best to respond here, as there was a naval blockade of Japan that was being pursued around the end of the war, along with other multivalent axes of attack on Japan and its economy (fire-bombings of cities, carrier raids on Japanese outlying islands and infrastructure, a planned land invasion, and of course the use of the atomic bombs). American submarines had been intensively attacking Japanese shipping since the start of the war, and American submarines sank something like 4.8 million tons of Japanese shipping over the course of the war. This section of our FAQ focuses on the end of the war and the factors most responsible for Japanese surrender.

Regarding Allied European nations sending ships, the British Pacific Fleet operated in the Pacific starting in late 1944 -- the capital ships were all British but other Commonwealth nations contributed smaller ships and auxiliaries.