@plainoldme,
This is what wiki has to say:
At first glance, it appeared that the U.S. had military treaty obligations to both parties in the war, bound to the UK as a member of the North Atlantic Treaty Organization (NATO) and to Argentina by the Inter-American Treaty of Reciprocal Assistance (the "Rio Pact"). However, the North Atlantic Treaty only obliges the signatories to support if the attack occurs in Europe or North America north of the Tropic of Cancer, and the Rio Pact only obliges the U.S. to intervene if one of the adherents to the treaty is attacked—the UK never attacked Argentina, only Argentine forces on British territory. In March, Secretary of State Alexander Haig directed the United States Ambassador to Argentina to warn the Argentine government away from any invasion. President Reagan requested assurances from Galtieri against an invasion and offered the services of his Vice President, George H.W. Bush, as mediator, but was refused.
In fact, the Reagan Administration was sharply divided on the issue. Meeting on April 5, Haig and Assistant Secretary of State for Political Affairs Lawrence Eagleburger favoured backing Britain, concerned that equivocation would undermine the NATO alliance. Assistant Secretary of State for Inter-American Affairs Thomas Enders, however, feared that supporting Britain would undermine U.S. anti-communist efforts in Latin America. He received the firm backing of U.N. Ambassador Jeane Kirkpatrick, Haig's nominal subordinate and political rival. Kirkpatrick was guest of honour at a dinner held by the Argentine ambassador to the United States, on the day that the Argentine armed forces landed on the islands.
The White House continued its neutrality; Reagan famously declared at the time that he could not understand why two allies were arguing over "that little ice-cold bunch of land down there". But he assented to Haig and Secretary of Defense Caspar Weinberger's position. Haig briefly (April 8–April 30) headed a "shuttle diplomacy" mission between London and Buenos Aires. According to a BBC documentary titled "The Falklands War and the White House",[18] Caspar Weinberger's Department of Defense began a number of non-public actions to support and supply the British military while Haig's shuttle diplomacy was still ongoing. Haig's message to the Argentines was that the British would indeed fight, and that the U.S. would support Britain, but at the time he was not aware that the U.S. was providing support already.
At the end of the month, Reagan blamed Argentina for the failure of the mediation, declared U.S. support for Britain, and announced the imposition of economic sanctions against Argentina.
In a notorious episode in June, U.S. Ambassador to the United Nations Jeane Kirkpatrick cast a second veto of a Security Council resolution calling for an immediate cease-fire, then announced minutes later that she had received instructions to abstain. The situation was blamed on a delay in communications but perceived by many as part of an ongoing power struggle between Haig and Kirkpatrick.
Galtieri and a fair proportion of his government thought that the UK would not react. Margaret Thatcher declared that the democratic rights of the Falkland Islanders had been assaulted and would not surrender the islands to the Argentinian "jackboot". This stance was aided, at least domestically, by the mostly supportive British press.
The Argentine dictatorship felt that the United States would, even in a worst-case scenario, remain completely neutral in the conflict (based upon the support that Argentina had given to the Reagan administration in Central America, training Contras). This assumption demonstrated a clear blindness to the reality of the US-UK special relationship.
To some extent, the Argentine military dictatorship was misled by its own opinion of democracies as being weak, inefficient talking-shops, afraid of taking risks. Indeed, in Britain there was much debate about the rights and wrongs of war. However, regardless of their own policies and opinions, opposition parties firmly backed the government during the crisis, in order to present a single united front.
A U.S. fear of the perceived threat of the Soviet Union and the spread of communism, along with the certainty that Britain could handle the matter on its own, may have influenced the U.S. to take a position of non-interference. During the Cold War, with the performance of forces being watched closely by the Soviet Union, it was considered preferable for the UK to handle without assistance a conflict within its capabilities.[citation needed]
Caspar Weinberger
American non-interference was vital to the American-British relationship. Ascension Island, a British possession, was vital in the long term supply of the Task Force South; however, the airbase stationed on it was run and operated by the U.S. The American commander of the base was ordered to assist the British in any way and for a brief period Ascension Air Field was one of the busiest airports in the world. The most important NATO contributions were intelligence information and the rescheduled supply of the latest model of Sidewinder Lima all-aspect infra-red seeking missiles, which allowed existing British stocks to be employed. Margaret Thatcher stated that "without the Harrier jets and their immense manoeuvrability, equipped as they were with the latest version of the Sidewinder missile, supplied to us by U.S. Secretary of Defense Caspar Weinberger, we could never have got back the Falklands." This is not only politically but militarily questionable, however, as all the Fleet Air Arm Sidewinder engagements proved to be from the rear.
In early May, Casper Weinberger offered the use of an American aircraft carrier.[19] This seemingly extremely generous offer was seen by some as vital: it was noted by Rear Admiral Woodward that the loss of Invincible would have been a severe setback, but the loss of Hermes would have meant an end to the whole operation. Weinberger admits [20] that there would have been many problems if a request had ever been made; not least, it would have meant U.S. personnel becoming directly involved in the conflict, as training British forces to crew the vessel would have taken years.
Both Weinberger and Reagan were later awarded the British honour of Knight Commander of the British Empire (KBE). American critics of the U.S. role claimed that, by failing to side with Argentina, the U.S. violated its own Monroe Doctrine.
In September 2001, the President of Mexico Vicente Fox cited the conflict as proof of the failure of the Inter-American Treaty of Reciprocal Assistance since the treaty provides for mutual defence. However, in this conflict, Argentina was the aggressor.