Through September, concerns about the Soviet troop presence in Cuba among members of Congress and the general public grew increasingly pronounced. U.S. Secretary of State Cyrus Vance met five times with Soviet ambassador Anatoly F. Dobrynin and twice with Soviet Foreign Minister Andrei Gromyko in an effort to persuade the Soviets to withdraw the troops, but Moscow made it clear that it was unwilling to do so, insisting that the brigade was there only to train Cuban military personnel.

The Soviet refusal left the White House in a political bind, since Carter had publicly stated that “this status quo is not acceptable.” Dogged throughout his presidency by criticisms that he was an unsteady leader who lacked the backbone to stand up to the Soviets, Carter faced enormous pressure to act firmly in order to shore up support for SALT II. At the same time, the president understood that there was nothing he could do to force the Soviets to remove the brigade without causing U.S.-Soviet relations to deteriorate further – a development that also would have undermined support for the treaty in the Senate.

On Oct. 1, Carter spoke to the American people about the situation in a nationally televised address. Seeking to walk a fine line between appearing too concerned and too unconcerned, he told the public that while the Soviet unit “presents no direct threat to us,” its presence in Cuba was nonetheless “a serious matter.”

He listed a number of steps the United States would take in response. These included the resumption of aerial surveillance flights over Cuba, the creation of a joint military task force responsible for the Caribbean, increased U.S. military exercises in the region, and expanded U.S. economic assistance to impoverished countries in Central America.

Carter also told the nation that Soviet officials had made “certain statements” to their American counterparts that the U.S. interpreted to mean that “they do not intend to enlarge the unit or to give it additional capabilities.” This was the closest thing that Carter could point to as a concession by Moscow.

None of the actions announced by Carter were particularly substantive – but, then again, neither was the supposed crisis they were intended to resolve. The president’s speech did little to change many minds about SALT II or U.S.-USSR relations generally, but the controversy began to slowly fade from view in the weeks following his address.

Political conditions in the U.S. in the fall of 1979 were such that the discovery of the brigade in Cuba was bound to set off a firestorm. Anti-Soviet hardliners who saw the USSR as an imminent, existential threat had succeeded in pushing American public opinion on foreign policy further and further to the right over the preceding years.

News of the Soviet forces in Cuba reached the public just a few weeks after Carter had submitted SALT II to the Senate for ratification. That the controversy unfolded shortly before the onset of the 1980 presidential campaign only added to the situation’s combustibility. Had the Soviet troops been detected a year or two earlier, it’s unlikely that it would have caused the furor that it did.

In the end, SALT II was never got a vote. The brigade issue delayed Senate action on the agreement until late 1979, by which time its fate was overtaken by events. The Soviets invaded Afghanistan at the end of December, and in response Carter officially asked the Senate to postpone its consideration of the treaty indefinitely.

His administration had planned to mount a renewed push for ratification at the start of his second term, but he lost his 1980 bid for reelection to Ronald Reagan, the favorite son of anti-Soviet hardliners and an expressed opponent of the treaty. Had the Soviet troops controversy not arisen, it is quite possible that SALT II would have been approved.

The uproar in the United States over the troops in Cuba was a strong indication that the era of détente was over. In his speech to the nation, Carter stated that “the brigade issue is certainly no reason for a return to the Cold War.” But it had never really ended, just diminished in intensity.

The improvements in superpower relations during the 1970s were real, but they were not enduring. Although it is little remembered today, this controversy in 1979 served as an unfortunate prelude to the dangerous tensions that existed between the United States and USSR in the early 1980s, a period during which the risk of nuclear war was as high as at any other moment in the Cold War.