They would verify the treaty without on-site inspections, using their own assets

Monday, November 7th, 2022

In 1972, the United States and Soviet Union signed the Anti-Ballistic Missile Treaty and the Interim Agreement, collectively known as SALT I:

This was an agreement by the two parties that they would verify the treaty without on-site inspections, using their own assets. Both sides also agreed not to interfere with these “national technical means.”

“National technical means” served as a euphemism for each country’s technical intelligence systems. Although these assets included ground, airborne, and other intelligence collection systems, the primary intelligence collectors for treaty verification were satellites, which both countries had been operating for over a decade, but neither country publicly discussed, certainly not with each other.


Surprisingly, there appears to have been little initial skepticism on the American side about the ability to verify strategic arms control treaties using satellites. In fact, there are indications that by the early 1970s there was an overestimation of their capabilities, although the people who developed and operated them were concerned about their limitations, as well as the misperception about what they could do versus their actual capabilities.

I’ve mentioned before that I always assumed that spy satellites used TV cameras, and it was a real shock to learn that they didn’t start out that way:

The first successful American photo-reconnaissance mission took place in August 1960 as part of the CORONA program. CORONA involved orbiting satellites equipped with cameras and film and recovering that film for processing. The early satellites orbited for approximately a day before their film was recovered, and it could take several days for that film to be transported and processed before it could be looked at by photo-interpreters in Washington, DC. Although the system was cumbersome, the intelligence data produced by each CORONA mission was substantial, revealing facilities and weapons systems throughout the vast landmass of the Soviet Union.

CORONA’s images were low resolution, capable of revealing large objects like buildings, submarines, aircraft, and tanks, but not providing technical details about many of them. In 1963, the National Reconnaissance Office launched the first GAMBIT satellite, which took photographs roughly equivalent to those taken by the U-2 spyplane that could not penetrate Soviet territory. Both CORONA and GAMBIT returned their film to Earth in reentry vehicles. By 1966, CORONA was equipped with two reentry vehicles, and GAMBIT was equipped with one, increased to two reentry vehicles by August 1969. The existence of multiple reentry vehicles on satellites and missiles was to become a source of concern for NRO officials as new arms control treaties were negotiated.

The two satellites complemented each other: CORONA covered large amounts of territory, locating the targets, and GAMBIT took detailed photographs of a small number of them, enabling analysts to make calculations about their capabilities such as the range of a missile or the carrying capability of a bomber. These photographic reconnaissance satellites provided a tremendous amount of data about the Soviet Union. That data was combined with other intelligence, such as interceptions of Soviet missile telemetry, to produce assessments of Soviet strategic capabilities. Signals and communications intelligence, collected by American ground stations around the world as well as satellites operated by the NRO, also contributed to the overall intelligence collection effort.

By the mid-to-late 1960s, these intelligence collection systems, particularly the photo-reconnaissance satellites, had dramatically improved American understanding of Soviet strategic forces and capabilities. A 1968 intelligence report definitively declared, “No new ICBM complexes have been established in the USSR during the past year.” As a CIA history noted, “This statement was made because of the confidence held by the analysts that if an ICBM was there, then CORONA photography would have disclosed them.” This kind of declared confidence in the ability of satellite reconnaissance to detect Soviet strategic weapons soon proved key to signing arms control treaties.


  1. Lu An Li says:

    Those first series of American photo reconnaissance satellites demonstrated that the so called bomber gap and missile gap was non existent.

    Intelligence reports the CIA and presumably others were feeding the President and other decision makers baaed on paranoid beliefs to a large extent without foundation.

  2. Gavin Longmuir says:

    I read somewhere that the main thing those first series of American photo reconnaissance satellites showed was that much of the Soviet Union was often covered by clouds.

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