Analysts with a sufficiently historical point of view tended to see in the Watergate affair and Nixon’s 1974 resignation the culmination of a 30-year trend by which war and the Cold War had greatly expanded, and ultimately corrupted, executive power. Liberals who, in Eisenhower’s time, had called for strong presidential leadership now bemoaned “the imperial presidency.” With what were widely understood to be the lessons of Vietnam fresh in the nation’s mind, and a majority in Congress and the press hostile to the sitting president, the moment arrived for a legislative counterattack on the executive. This interpretation is borne out by the subsequent congressional acts designed to limit executive freedom in foreign policy. The War Powers Act of 1973 restrained the president’s ability to commit U.S. forces overseas. The Stevenson and Jackson–Vanik amendments imposed conditions (regarding Soviet policy on Jewish emigration) on administration plans to expand trade with the U.S.S.R. In 1974–75 Congress prevented the President from involving the United States in a crisis in Cyprus or aiding anti-Communist forces in Angola and passed the Arms Export Control Act, removing presidential discretion in supplying arms overseas. New financial controls limited the president’s ability to conclude executive agreements with foreign powers, of which some 6,300 had been signed between 1946 and 1974 as compared with only 411 treaties requiring the Senate’s advice and consent. Finally, revelations of past CIA covert operations, including schemes to assassinate Fidel Castro, inspired complicated congressional oversight procedures for U.S. intelligence agencies. These assaults on executive prerogative were meant to prevent future Vietnams, prevent unelected presidential aides from engaging in secret diplomacy, and restore to Congress an “appropriate” role in foreign policy. Critics of the limitations held that no great power could conduct a coherent or effective foreign policy under such a combination of openness and restrictions, especially in a world populated increasingly by totalitarian regimes, guerrilla movements, and terrorists.

The Nixon–Brezhnev summits of 1973–74 produced only minor follow-ons in the area of arms control—the uncontroversial Agreement on the Prevention of Nuclear War and an agreement to reduce the number of ABM sites from the two permitted in 1972 to one. Gerald Ford, president from August 1974, and Henry Kissinger, who remained as secretary of state, attempted to restore the momentum of détente through a new SALT agreement regulating the dangerous race in MIRVed missiles, which SALT I had not prevented. The United States proposed strict equality in nuclear delivery systems and total throw weight, which meant that the United States would be allowed to MIRV more of its missiles to offset the greater size of Soviet missiles. Since the United States had no plans for a unilateral buildup in any case, however, the Soviets had no incentive to make such a concession. Instead, Ford and Brezhnev signed an Interim Agreement at Vladivostok in November 1974 that limited each side to 2,400 delivery vehicles, of which 1,320 could be MIRVed. While the Soviets claimed that this was a concession, since they declined to count the 90 British and French missiles aimed at them, the Soviets’ giant SS-18s, able to deliver up to 10 MIRVs, ensured the U.S.S.R. an advantage in ICBM warheads. The repeated failure to restrain the growth of Soviet offensive systems soon sparked fears that the United States might become vulnerable to preemptive attack.

Meanwhile, the mid-1970s brought to a logical conclusion the process of détente in Europe. Nixon and Kissinger, aware that the United States had seemed to ignore its European allies during the 10 years of Vietnam, declared 1973 “the year of Europe” and hoped to forestall NATO governments from bargaining with Moscow on their own. Watergate and the Arab–Israeli war of that year (the Yom Kippur War) turned this initiative into a public-relations failure, however. Instead, the United States was obliged to follow the European lead in the ongoing Conference on Security and Cooperation in Europe and negotiations toward a “mutual and balanced force reduction” treaty covering NATO and Warsaw Pact forces in central Europe. The climax of the security talks was the Helsinki summit of 35 nations in the summer of 1975 and an agglomeration of proposals divided into three “baskets.” (A fourth basket dealt with the question of a follow-up conference.) In Basket I the signatories accepted the inviolability of Europe’s existing borders and the principle of noninterference in the internal affairs of other states—thereby recognizing formally the Soviet gains in World War II and the Soviet-bloc states. Basket II promoted exchanges in science, technology, and commerce, expanding Soviet access to Western technology and opening the Soviet market to western European industry. Basket III, the apparent Soviet concession, aimed at expanding cultural and humanitarian cooperation among all states on the basis of respect for human rights. Not surprisingly, Western opinion of the Helsinki Accords, and of détente in general, came to rest heavily on whether the U.S.S.R. would voluntarily comply with Basket III. American leaders of both parties considered Helsinki misguided and empty, especially after Moscow stepped up the persecution of dissidents and jailed those of their citizens engaged in a “Helsinki watch” on Soviet compliance. In sum, Helsinki (and U.S. demands on behalf of Soviet Jews) pointed up another contradiction in détente, this time between American insistence on Soviet liberalization and Soviet insistence on noninterference in the domestic politics of other states.

Events in Southeast Asia and Africa

During final negotiations at Helsinki, events in Southeast Asia compounded the American sense of humiliation and growing discontent with détente. The North Vietnamese had never viewed the 1973 peace accords as anything other than an interlude permitting the final withdrawal of American forces. In the year following they built up their strength in South Vietnam to more than 150,000 regulars armed with Soviet tanks, artillery, and antiaircraft weapons. The ARVN was poorly trained, suffered from low morale after the Americans were gone, and faced an enemy able to attack at times and places of its own choosing. The American withdrawal also removed at a blow some 300,000 jobs from the local economy, and President Thieu made matters worse by trying to establish one-party bureaucratic rule without the charisma or prestige to sustain it. By October 1974 the Politburo in Hanoi concluded that the Saigon regime was ripe for collapse. Large-scale probes of ARVN defenses in January 1975 confirmed their optimism. By the end of the month 12 provinces and 8,000,000 people had fallen to the Communists. On April 10, unable to obtain congressional approval of $422,000,000 in further military aid, President Ford declared that the Vietnam War was over “as far as America is concerned.” The final North Vietnamese offensive reached Saigon on April 30, 1975, as the last remaining Americans fled to helicopters atop the U.S. embassy. Hanoi triumphantly reunified Vietnam politically in July 1976 and confined thousands of South Vietnamese to “reeducation camps,” while thousands of “boat people” risked death in the South China Sea to escape reprisals and Communism.

The end in Cambodia had already occurred. The Communist Khmer Rouge cut off the capital, Phnom Penh, in January 1975. When the U.S. Congress denied further aid to Cambodia, Lon Nol fled, and in mid-April the Khmer Rouge took control. Its leader, Pol Pot, was a French-educated disciple of Maoist “total revolution” to whom everything traditional was anathema. The Khmer Rouge reign of terror became one of the worst holocausts of the 20th century. All urban dwellers, including hospital patients, were forced into the countryside in order to build a new society of rural communes. Sexual intercourse was forbidden and the family abolished. More than 100,000 Cambodians, including all “bourgeois,” or educated people, were killed outright, and 400,000 succumbed in the death marches; in all, 1,200,000 people (a fifth of the Cambodian nation) perished. The Khmer Rouge, however, were not allied with Hanoi, and in 1979 PAVN forces invaded Cambodia to oust the Khmer Rouge and install a puppet regime. This action completed the conquest of Indochina by North Vietnam, for Laos, too, became Communist after the fall of Saigon. Thus the domino theory was at last put to the test and to a large extent borne out.

Events in Africa as well seemed to bear out the Soviet expectation that “progressive forces” would gain ground rapidly during the new era of superpower parity. Angola and Mozambique, coastal states facing the oil-tanker routes around the Cape of Good Hope, were finally slated to achieve independence from Portugal following a leftist military coup in Lisbon in April 1974. Three indigenous groups, each linked to tribal factions, vied for predominance in Angola. The MPLA (Popular Movement for the Liberation of Angola) of Agostinho Neto was Marxist and received aid from the U.S.S.R. and Cuba. The FNLA (National Front for the Liberation of Angola) in the north was backed by Mobutu Sese Seko of Zaire (now the Democratic Republic of the Congo) and initially by a token contribution from the CIA. In the south the UNITA (National Union for the Total Independence of Angola) of Jonas Savimbi had ties to China but came to rely increasingly on white South Africa. In the Alvor agreement of January 1975 all three agreed to form a coalition, but civil war resumed in July. By the end of the year the MPLA had been reinforced by 10,000 Cuban soldiers airlifted to Luanda by the U.S.S.R. In the United States the imperative of “no more Vietnams” and congressional ire over CIA covert operations frustrated Ford’s desire to help non-Communist Angolans. Neto accordingly proclaimed a People’s Republic of Angola in November 1975 and signed a Treaty of Friendship with the U.S.S.R. the following October. The rebel factions, however, remained in control of much of the country, and Cuban troop levels eventually reached 19,000. A Marxist government also assumed power in Mozambique.