Treaty of Versailles, why wasn't it checked upon?

When talking about Nazi Germany and the role of the Treaty of Versailles in gaining Hitler popularity, one must remember that the Treaty had been revised twice between 1919 and 1933, the first time being the Dawes Plan in 1924, and the second being the Young Plan in 1929.

In terms of 'why didn't the Allies check up on Germany', there is a substantial argument that the Allies were in no serious position to command Germany do anything. The 1930s had seen a massive economic downturn in most Capitalist countries, and the resulting rise of Fascism in Italy and Japan had resulted in massive worldwide crisis' in Manchuria and Abyssinia. When this is coupled with America's steadfast position of Isolationist foreign policy had meant that the old Allied powers simply could not stand up to the aggressive Hitler.

One must also acknowledge that there was a sense in Western Europe that a strong Germany might not have been such a bad thing. Most of Europe's populace saw the rise of Eastern Communism as a much greater threat than Hitler. As such, the idea of Germany increasing the buffer between East and West was quite a welcome.

Finally, most individuals in Britain and the U.S had begun to feel that the Treaty of Versailles had been too harsh on Germany and were almost happy to allow Hitler to eradicate some of the more harshest areas of the treaty.

They had other fish to fry. Even if they wanted to threaten Germany with military intervention, they were in no shape to start a war. There were far more pressing concerns and after 15 years the whole "Germany will pay" had lessened a bit from its 1920 level.