Carter Doctrine

The Carter Doctrine was a policy proclaimed by President of the United States Jimmy Carter in his State of the Union Address on January 23, 1980, which stated that the United States would use military force, if necessary, to defend its national interests in the Persian Gulf. It was a response to the Soviet Union's intervention in Afghanistan in 1979, and it was intended to deter the Soviet Union, the United States' Cold War adversary, from seeking hegemony in the Persian Gulf region.
The following key sentence, which was written by Zbigniew Brzezinski, President Carter's National Security Adviser, concludes the section:
Let our position be absolutely clear: An attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America, and such an assault will be repelled by any means necessary, including military force.
Brzezinski modeled the wording on the Truman Doctrine, and insisted the sentence to be included in the speech "to make it very clear that the Soviets should stay away from the Persian Gulf."
In "", author Daniel Yergin notes that the Carter Doctrine "bore striking similarities" to a 1903 British declaration in which British Foreign Secretary Lord Landsdowne warned Russia and Germany that the British would "regard the establishment of a naval base or of a fortified port in the Persian Gulf by any other power as a very grave menace to British interests, and we should certainly resist it with all the means at our disposal."
Background.
The Persian Gulf region was first proclaimed to be of national interest to the United States during World War II. Petroleum is centrally important to modern armies. The United States, the world's leading oil producer at the time, supplied most of the oil for the Allied armies. Many American strategists were concerned that the war would dangerously reduce the US's oil supply and so they sought to establish good relations with Saudi Arabia, a kingdom with large oil reserves. On February 16, 1943, US President Franklin Roosevelt said, "the defense of Saudi Arabia is vital to the defense of the United States." 
On February 14, 1945, while he was returning from the Yalta Conference, Roosevelt met with Saudi Arabian King Ibn Saud on the Great Bitter Lake in the Suez Canal, the first time a US president had visited the Persian Gulf region. During Operation Desert Shield in 1990, US Defense Secretary Dick Cheney cited the landmark meeting between Roosevelt and Ibn Saud as one of the justifications for sending troops to protect Saudi Arabia's border.
The Persian Gulf region was still regarded as an area of vital importance to the US during the Cold War. Three Cold War American presidential doctrines (the Truman, Eisenhower, and Nixon Doctrines) played roles in forming the Carter Doctrine. The Truman Doctrine, which stated that the US would send military aid to countries threatened by Soviet communism, was used to strengthen both Iran and Saudi Arabia's security. In October 1950, President Truman wrote to Ibn Saud that "the United States is interested in the preservation of the independence and territorial integrity of Saudi Arabia. No threat to your Kingdom could occur which would not be a matter of immediate concern to the United States." 
The Eisenhower Doctrine called for US troops to be sent to the Middle East to defend US allies against their Soviet-backed adversaries. Ultimately, the Nixon Doctrine's application provided military aid to Iran and Saudi Arabia so that US allies could ensure peace and stability there. In 1979, the Iranian Revolution and the Soviet intervention of Afghanistan prompted the restatement of US interests in the region in the form of the Carter Doctrine.
In July 1979, responding to a national energy crisis, President Carter delivered his "Crisis of Confidence" speech, urging Americans to reduce their energy use to help lessen American dependence on foreign oil supplies. Recently, some scholars have claimed that Carter's energy plan, if it had been fully enacted, would have prevented some of the current economic difficulties caused by the American dependency on foreign oil.
The doctrine.
President Carter, in his State of the Union Address on January 23, 1980, after stating that Soviet troops in Afghanistan posed "a grave threat to the free movement of Middle East oil," proclaimed:
Implementation.
The Carter administration began to build up the Rapid Deployment Force, which would eventually become CENTCOM. In the interim, the administration asked Congress to restart Selective Service registration, proposed a five percent increase in military spending for each of the next five years, and expanded the US naval presence in the Persian Gulf and the Indian Ocean.
A negative response came from retired strategist George F. Kennan. United States Senator Edward Kennedy charged that Carter had overreacted, exaggerated the Soviet threat, and failed to act diplomatically. Kennedy repeated these allegations during his 1980 Democratic presidential primary bid, in which he was defeated.
Carter's successor, Ronald Reagan, extended the policy in October 1981 with what is sometimes called the "Reagan Corollary to the Carter Doctrine," which proclaimed that the United States would intervene to protect Saudi Arabia, whose security was believed to be threatened during the Iran–Iraq War. Thus, while the Carter Doctrine warned away "outside" forces from the region, the Reagan Corollary pledged to secure "internal" stability. According to diplomat Howard Teicher, "with the enunciation of the Reagan Corollary, the policy groundwork was laid for Operation Desert Storm."