While waiting for a new answer, I can point you to a similar question that I asked a few years ago, Why not blockade Japan by sea in WWII?, with a great answer by u/DBHT14
Since we’re on the topic, a related question is why was it decided to drop the bombs on the cities themselves? Could they not have dropped the bombs within the proximity of a major city to make a statement instead? Did they think that the threat of killing civilians wouldn’t be enough to get the Japanese to consider surrendering?