Jimmy Carter weighed the risk of ending all nuclear tests in 1977

By Roy Castellano · August 17, 2026

A Secret memorandum shows the new president wanted to stop all nuclear explosions, leaving the military to figure out if the Soviets would actually stop too.

Every man stationed at the Nevada Test Site or the bunkers of the Pacific knew that the peace of the Cold War rested on a series of violent, measured explosions. If those explosions stopped, the gamble shifted from the scientists to the crews waiting in the silos, who had to trust that their warheads would actually fire when the order came.

For the analysts at Strategic Air Command, the technical viability of a weapon was not a matter of diplomatic goodwill, but of survival. A deterrent that cannot be verified is not a deterrent; it is a prayer. On January 25, 1977, that prayer was codified in a Secret Presidential Review Memorandum, known as NSC–161, which tasked the highest levels of the American security state with imagining a world where the testing of all nuclear devices simply ceased.

February 9

President Jimmy Carter did not leave much time for the experts to weigh the risks. The memorandum, addressed to the Vice President, the Secretary of State, the Secretary of Defense, and other senior officials including the Director of Central Intelligence and the Chairman of the Joint Chiefs of Staff, set a deadline of February 9 for a preliminary review.

Carter’s directive was blunt. He wanted an immediate follow-up to his public remarks concerning the "elimination of testing of all nuclear devices." He ordered the Special Coordination Committee to analyze the "major problems of verifying a complete ban" on all tests—including both weapons and what the government termed "peaceful nuclear explosions"—by the United States, the USSR, and other nuclear-armed nations.

To a war-plans analyst, the word "verifying" is where the real story begins. In the world of nuclear deterrence, you do not trust the word of the Kremlin; you trust the seismic sensors and the atmospheric samples. Carter’s request for a "preliminary analysis" of verification problems suggests an awareness that a total ban might be a diplomatic victory that created a strategic nightmare.

"Seriousness of purpose"

Behind the formal requests of the memorandum was a political urgency. A cover memorandum from Zbigniew Brzezinski advised Carter to sign the document "immediately." The goal was not merely to gather data, but to "show the seriousness of your purpose" to end the testing cycle.

This framing reveals the tension inherent in the transition of power in 1977. The desire to project moral leadership on the world stage often collided with the cold requirements of the nuclear triad. The memorandum asked for an examination of "alternative diplomatic scenarios," including the possibility of a unilateral US moratorium or a bilateral agreement with the Soviets.

For those of us who spent years mapping the targets and fueling the bombers, the idea of a unilateral moratorium is an invitation to catastrophe. It signals to an adversary that you are more interested in the appearance of peace than the preparation for war. By asking for the "advantages and disadvantages" of such a move, Carter was forcing the Joint Chiefs and the DCI to put a price tag on diplomacy.

Who verifies the ban?

Beyond the grand gestures, the record shows a preoccupation with the existing legal framework. The document references the 1963 Limited Test Ban Treaty, which had already pushed nuclear explosions out of the atmosphere, outer space, and underwater. It also points to the 1974 Threshold Test Ban Treaty, which limited underground tests to a yield of 150 kilotons.

But the 1977 memorandum pushed further. It sought to understand the "effect of such a ban on US weapons testing programs as well as the likely effect on Soviet programs." This is the fundamental question of the arms race: if we stop, do they stop? If they stop, can we prove it?

There is a specific danger in the gap between a moratorium and a treaty. A moratorium is a promise; a treaty is a contract. The memorandum weighed whether to amend the Limited Test Ban Treaty to make the cessation of testing permanent. Until such a mechanism exists, a ban is merely a period of blindness during which an opponent can refine their arsenal in secret.

Peaceful Nuclear Explosions

Perhaps the most curious aspect of the review was the status of the PNE Agreement. Signed in 1976, this agreement allowed the US and the USSR to conduct underground nuclear explosions for "peaceful purposes," provided they did not enjoy "weapons-related benefits" from them.

Carter’s memorandum asked the Special Coordination Committee to determine whether the administration should move ahead with or "hold" the Threshold Test Ban Treaty and the PNE Agreement already before Congress. This suggests a hesitation—a moment where the administration wondered if the pursuit of a total ban would undermine the specific, limited agreements already in place.

The document leaves the final decision unrecorded, focusing instead on the process of the review. It leaves us with the image of a new president urging his generals and spies to find a way to stop the bombs from blowing, while his advisors worried about how that desire would look to the rest of the world. Whether the "seriousness of purpose" outweighed the risks of strategic blindness remained a question for the analysts to answer by February 9.