[captainperl]

> Because as I understand it, the US was largely aloof until Germany started pursuing atomic weapons ...

No. The USA public was isolationist until the bombing of Pearl Harbor. Germany stupidly declared war after Pearl Harbor in sympathy with Japan.

The key things to understand about WW2 are:

1) Germany and Japan declared war on a country they couldn't invade because of geography.

In other words, the USA did not have enough deterrence at the time to prevent WW2. [paraphrasing Victor David Hanson]

The B-29 was the ultimate weapon in WW2, not the atomic bomb (which was dropped from a B-29.) So much so that Russia spent vast resources after WW2 copying it down to the last rivet.

2) The USA was already the "arsenal of democracy" a year before Pearl Harbor. Historians regard Pearl Harbor as more of a trap than a victory for the Japanese, which would have required both sinking all of America's carriers plus a successful land invasion of Oahu to end well.

3) All sides thought that bombing the enemy's cities would break their will to fight. As any chess player knows, people will fight to the bitter end with very few exceptions.