Weinberger Doctrine

The Weinberger Doctrine was a list of points governing when the United States could commit troops in military engagements. The doctrine was publicly disclosed by U.S. Secretary of Defense Caspar Weinberger on November 28, 1984, in a speech entitled "The Uses of Military Power" delivered before the National Press Club in Washington, D.C.
The Weinberger Doctrine was an outgrowth of the collective lessons learned from the Vietnam War and the desire of the U.S. government to avoid such quagmires in the future.
The Weinberger doctrine:
Political background.
Two unconnected events led to Weinberger's speech. One was his wanting to respond to the 1983 Beirut barracks bombing, in which 241 United States Marines, Sailors, and Soldiers died. U.S. forces were in Lebanon as part of an ill-fated U.S. peace enforcement mission undertaken despite the reportedly vigorous opposition of the U.S. Secretary of Defense and the U.S. Joint Chiefs of Staff who argued that its purpose was never clearly defined and that the chaotic, violent situation in Lebanon could not be brought under control by any outside force. They further argued that any U.S. military contingent entered into the Lebanon conflict would become a convenient and prominent target for the various factions in the civil war. The second event was the invasion of Grenada on October 25, 1983. U.S. and allied forces invaded Grenada after a pro-Soviet military coup ousted the constitutional government.
An older event, but one which probably had a stronger influence on U.S. foreign policy, Presidential powers, and the commitment of U.S. military forces which may have precipitated articulation of the Weinberger Doctrine, was the legacy of the Vietnam War. From 1975 and the fall of South Vietnam to Communist forces, U.S. foreign policy had avoided the use of military force, without any officially stated policy for how to employ those powers.
Opposition.
Not everyone agrees with these principles. Notably, the Secretary of State at the time of the Doctrine's publishing, Secretary of State George Shultz, "took strong public objection to them". He worried that without credible threats of military action, "American diplomacy...would be hamstrung by the military's supposed reluctance to become involved in 'limited' wars". 
In his memoirs, An American Life, Ronald Reagan listed these principles and said they helped guide his Administration's foreign policy decisions. He recommended them to future Presidents. 