Revival of militarism.... why?

My question is why on earth after this huge devastating war did miliartism develop again? The was one of the biggest causes of WWI and that was known at the time. Feeble attempts like the League of Nations were ineffective because it had no real power. To me the idea of a League of Nations can never really work very well because it's essentially asking nations to give up power over themselves to other nations. The League of Nations was also largely ineffective in solving political disputes because of the absence of many nations that were crucial to rebuilding the world after WWI. The League of Nations was to me the only attempt at controlling miliarism at this time, at it was mostly effective at helping social welfare, not political disputes. The countries that were involved should've learned the consequences of miliartism after the first World War but they didn't, why? Could it be because they were too selfish and defensive after the war that they couldn't let go of their defenses? Germany, as a loser of the war, was restricted in it's miliary buildup but upon seeing the United States ignore treaties decided to do the same. Why did treaties suddenly not mean anything? Was the world in such turmoil that old customs didn't seem relevant anymore?