There is no conflict between Ireland's military neutrality and full and active support by Ireland for collective security based on international law. The progressive approach taken by Éamon de Valera in the League of Nations in the 1930s is clear evidence of that. When faced with the challenge to international security of Mussolini's invasion of Abyssinia, Ireland supported sanctions against Mussolini. The League of Nations was, however, unable to deal effectively with aggressor states led by dictators because of the absence from the League of the United States and the weakness of the League's enforcement mechanisms. As the League of Nations failed to meet its responsibilities, the world descended into war.