The League of Nations was formed after World War I (1914-1919) and was dissolved by the beginning of World War II (1939). It was an intergovernmental organization founded as a result of the Paris Peace Conference that ended World War I, and it was the precursor to the United Nations.
The League was the first permanent international security organization whose principal mission was to maintain world peace. It had 58 members. The League's primary goals included preventing war through collective security, disarmament, and settling international disputes through negotiation and arbitration. Germany, under Hitler, withdrew from the League and was followed by other nations. WWII showed that the League had failed its primary purpose, which was to avoid a future world war.
The name "United Nations" was devised by US president Franklin D. Roosevelt following World War II and set up as another world organization for preventing future wars. The United Nations officially came into existence in October 1945, when the Atlantic Charter had been ratified by China, France, USSR, UK, and a majority of other signatories. It has 192 members. The main purposes of the United Nations are to facilitate cooperation in international law, international security, human rights, social progress and accomplish world peace.
North Atlantic Treaty Organization or NATO, also called the North Atlantic Alliance, is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defense where its members agree to mutual defense in response to an attack by any external party. It has 28 members. The Korean War galvanized the member states, and an integrated military structure was built up under the direction of two US supreme commanders.
The combined military spending of all NATO members constitutes over 70% of the world's defense spending. The United States accounts for 43% of the total military spending of the world and the United Kingdom, France, Germany, and Italy account for another 15%.
The six-member Shanghai Cooperation Organization (SCO) was set up in 2001 by China, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Uzbekistan to address religious extremism and border security in Central Asia, and as a security counterweight to NATO that would allow Russia and China to rival US influence in Asia. It is now also looking to cooperate at an economic level. Its membership includes the ex-Soviet Central Asian states and with India, Iran, Mongolia and Pakistan attending meetings as observers. Its summits bring together an eclectic gathering of world leaders. In a recent summit declaration signed by all the member states, the organization also attacked missile defense programs in another apparent dig at the United States.
According to Defense Secretary Gates this past week, NATO may have a dim future and may no longer be worth the cost to the US.