Nixon first used the Hot Line during the brief 1971 Indo-Pakistani War. The president and his national security adviser, Henry Kissinger, initially worked through diplomatic channels to ask the Soviets to both restrain India and help the United States end the crisis.
Concerned when General Secretary Leonid Brezhnev failed to respond promptly, Nixon emphasized his point by messaging Brezhnev on the Hot Line. Brezhnev responded positively the next day, and the hostilities wound down.
That same year, the Nixon administration agreed with Moscow to upgrade the Hot Line circuit by adding satellite links: one via the U.S. Intelsat system, and another using the Soviet Union Molniya II satellites.
The outbreak of the 1973 "Yom Kippur War," another Arab-Israeli conflict, challenged a wounded president in the midst of his Watergate woes.
Egypt and Syria attacked Israel on Oct. 6, 1973 - Yom Kippur, the Day of Atonement. Israel fared badly in the early going but later gained the upper hand. That prompted the Soviet Union to threaten intervention in support of Egypt and Syria.
Brezhnev sent a Hot Line message to Washington at 9:35 p.m. on Oct. 24. He threatened Soviet military action if Israel did not stop fighting. Nixon, depressed by the deterioration of his presidency, had retreated by that time to the White House residence and the solace of a few highballs. Taking receipt of Brezhnev's message, Kissinger, then both secretary of state and national security adviser, spoke on the telephone with presidential Chief of Staff Alexander Haig.
"I just had a letter from Brezhnev asking us to send forces in together or he would send them in alone," Kissinger said.
"I was afraid of that," Haig said.
"Should I wake up the president?" Kissinger asked.
Kissinger, Haig and five other members of Nixon's crisis-management team decided on a response. They raised the worldwide readiness level of U.S. military forces and put the 82nd Airborne Division on alert. After the Soviets had time to observe those actions, Kissinger, on behalf of Nixon, sent a nonconfrontational Hot Line response to Brezhnev's letter.
The Soviets quickly pulled back, and Israel finally halted hostilities.
Shortly before Nixon's August 1974 resignation, Kissinger used the Hot Line during a July confrontation between Greece and Turkey over Cyprus. With Nixon closeted in his California home and contemplating resignation, Kissinger dealt with Moscow.
Zbigniew Brzezinski talked with me recently about President Carter's use of the Hot Line. The former national security adviser and I melded my research with his recollections from 34 years ago, and agreed that Carter had used the Hot Line on three occasions.
The first instance, in September 1979, the matter was the purported U.S. discovery of a Soviet combat brigade in Cuba. The intelligence report came during the delicate attempt by Carter to persuade the Senate to ratify the SALT II disarmament agreement. Sen. Frank Church, D-Idaho, whose support Carter needed, latched on to the issue. He publicly called for Carter to "draw the line on Russian penetration of this hemisphere."
Carter sent two Hot Line messages to Brezhnev, the first on Sept. 24, then another when the Soviet did not immediately reply. Carter objected to the brigade's presence and noted that the situation might upset SALT II ratification.
Declassified minutes of the Soviet Politburo's meeting on Sept. 27 revealed Brezhnev's reaction: "Last night Carter once again appealed to us via the hot line regarding the issue of the story they have dreamed up about the presence of our military brigade in Cuba." Brezhnev's description of Carter's "dream" wasn't far off. The brigade was actually a remnant of Soviet forces deployed to Cuba before the 1962 Cuban missile crisis. The unit was not new to the Caribbean, but Washington politicians made it a new problem.
Brezhnev sent Hot Line assurances about the brigade's mission. The Washington Post's Don Oberdorfer reported that the Soviets could "be of little help in resolving what they believed to be essentially an American political problem, not of their making."
When, on Dec. 25, 1979, the Soviet Union invaded Afghanistan, the Cuban brigade brouhaha - to saying nothing of SALT II - quickly fell off the table.
Within days, Carter sent a Hot Line message to Brezhnev, one he later described as "the sharpest message of my presidency." Brezhnev replied the next day and waved aside rumors of an "invasion." He said the Afghan government had requested Soviet help.
The third time Carter fired up the Hot Line occurred on Dec. 3, 1980, a month after Reagan had defeated him. The Soviets appeared ready to invade Poland to quash the Solidarity movement. Carter warned of "serious consequences." And oddly closed with: "Best wishes, Jimmy Carter."
The Soviets eventually eased away from an assault.