Military intervention is a phenomenon where an outside party gets involved militarily in another country with the purpose of righting or preventing some perceived injustice. It could also be applied in tandem with humanitarian intervention, where an intervening force aims to aid in a pressing crisis brought on by conflict or a natural disaster where there is a need to alleviate famine, structural damage or potential social conflict. The act of military intervention might also involve extended occupation by military forces typically in terms of peacekeeping.
The use of military means to influence situations has been used throughout history, typically in response to threats against a country's interests or allies. In the late 19th century, the United States cited Spanish suppression of Cuban rebels to justify the Spanish-American War, which ended in the American domination of the Caribbean and the Philippines. Theodore Roosevelt, who had resigned his position as Secretary of the Navy to lead a battalion in Cuba, later advocated intervention against the Ottoman Empire's treatment of Armenians in order to launch the United States' involvement in World War I.
In response to these events, a precedent was created whereby the new United Nations could authorize the use of force to prevent such incidents. In 1950, with the People's Republic of China boycotted by the United Nations and the Soviet Union largely absent from proceedings, the Security Council authorized the use of force to intervene in the Korean civil war, effectively aligning the United Nations with American-supported South Korea. In response to this the Soviet Union decided to once again become involved in the United Nations in order to counterbalance American and British influence in the world body.
From there, the United Nations Security Council became the setting for heavily politicized international conflicts and was asked to intervene to separate hostile forces. Following the British withdrawal from the Middle East and India, peacekeepers were deployed to Israel and the Indian-Pakistani border. The Middle East has particularly been an important theater for military intervention, where peacekeepers have been deployed to separate Israeli forces from the enemy states of Egypt, Lebanon and Syria.
The United Nations has been criticized for the passive and non-aggressive tactics of their peacekeepers. In 1967, the United Nations acquiesced to an Egyptian demand to vacate the Sinai Peninsula. This action directly precipitated the Six Day War, which was later ambiguously condemned by the United Nations, inviting accusations of hypocrisy. Since 2006, Israel has criticized UNIFIL , the United Nations peacekeeping mission in Lebanon, for not enforcing resolutions demanding the disarmament of Hezbollah, prevention of its rearmament and the assurance that the security of the region is in the hands of Lebanon's regular army.
The United Nations has also been criticized as ineffective in a number of other theaters. Since the end of the cold war, the United Nations has shifted its peacekeeping philosophy to include areas where no clear mandate or agreement has been given by local authorities and has been authorized by the United Nations itself. Areas of deployment of peacekeepers have included Somalia in 1993, Rwanda in 1994 and Bosnia in 1995. All three areas were sites of humanitarian tragedies due to the civil war in Somalia, the Rwandan genocide (where peacekeepers actively avoided confrontation) and the Srebrenica massacre. In response to these incidents, the United Nations has taken reduced responsibility for a number of international military actions. In Bosnia in particular, NATO, the North Atlantic Treaty Organization, won authorization for an air campaign that suppressed the Bosnian Serbs and forced an end to the Bosnian civil war. Subsequently, 60,000 troops occupied the region to stabilize it.
NATO has become more active in international peacekeeping missions and humanitarian interventions since the end of the cold war and primarily since the intervention in Bosnia. Again in 1998, NATO intervened on the side of rebel Kosovo in the region. Following the American invasion of Afghanistan in 2001, NATO accepted responsibility for the country's mandate as a way of internationalizing American efforts to stabilize the country and defeating the insurgent Taliban. In 2011, with the urging of France and the reluctance of the United States, the organization launched an extensive air campaign against Muammar Qaddafi's Libya in order to protect Libyan civilians from his forces. The campaign enforced a United Nations-mandated no-fly zone to prevent aerial assault on civilians in rebel areas. The operation was criticized as having tremendous political overtones.