The alternatives to either invasion or atomic bombing are covered in the previous counterpoint. It can only be said that none of them are without a high human cost, though invasion spearheaded by an atomic barrage is surely the worst. The principle of advantage of the conventional bombing option being that it would be easily justifiable as only quantitively different to what the Japanese had already meted out themselves. The blockade similarly has easy justification in not being a deviation from any accepted standards as well as only indirectly attacking the home islands while putting the onus on the Japanese government to avoid starvation. Really in order to find a less costly alternative then diplomacy has to be raised for which refer to the second response argument.