[graemep]

Even with the obvious danger the Nazis presented it took a long time for most countries to respond. Britain and France could have stopped them (from a much stronger position) earlier but did nothing until after they had conquered Austria, Czechoslovakia, and Poland) and very little until the Nazis actually invaded France. The US did not enter the war until it was attacked either. Nor did the Soviet Union.

There was reluctance to act on an obvious and imminent threat. People just hoped it would go away.