Which National Security Archive documents reveal U.S. nuclear planning or deployments related to Thule Air Base between 1951 and 1968?

1. The 1951 Technical Schedule: the legal and geographic basis for U.S. access

The Archive posts the Top Secret “Technical Schedule” attached to the 27 April 1951 U.S.–Denmark Agreement, which identifies Thule (along with Narsarsuaq and Sondrestrom) as primary strategic areas reserved for U.S. use and explains the basis—secret at the time—for U.S. military activities in Greenland that underpinned later overflight and basing practices ^[1].

2. Airborne alert and Thule monitor missions documented in Archive briefings

The National Security Archive’s June 2025 briefing book on U.S. activity in Greenland summarizes declassified evidence that Strategic Air Command flew nuclear-armed B‑52s on continuous airborne-alert and “Thule monitor” missions beginning around 1961 and that SAC used those missions to provide 24‑hour warning coverage tied to the BMEWS radar at Thule ^[3].

3. Secret reports and “Broken Arrow” messages from the 1968 crash

Primary accident documentation released by the Archive includes the Thule Air Base “Supplemental Report No. 1 of Nuclear Accident (Broken Arrow)”—Message 4683ABGP—dated 22 January 1968, a Secret Air Force report giving early cause, munition loadout, and crew information about the B‑52 crash that dispersed plutonium on the ice ^[2].

4. Diplomatic memoranda and negotiations revealing storage/overflight disputes

Declassified State Department and White House files compiled by the Archive and in FRUS excerpts show internal U.S. negotiating positions after the crash—records noting U.S. claims of the right to overfly or store nuclear weapons “subject to Danish approval (unilaterally in case of emergency)” and describing Denmark’s push for absolute guarantees to bar nuclear storage and overflights ^{[5] [4]}.

5. Archive narrative collections that synthesize deployments and stocks

The Archive’s two‑part series “The United States and Greenland: Episodes in Nuclear History” assembles primary documents and analytical narrative that state the U.S. quietly stationed nuclear bombs at Thule by 1958, maintained warhead stocks through the early 1960s, and only later faced public and parliamentary scrutiny after the 1968 crash ^{[3] [6] [4]}.

6. Accident cleanup, technical reports and corroborating records

Beyond Archive-hosted diplomatic papers, the Archive and linked repositories reference technical and USAF cleanup documents (e.g., Project Crested Ice / USAF radiological annexes) and CIA/DoD estimates that together corroborate the presence of nuclear weapons on flights and facilities tied to Thule during the period ^{[7] [8]}.

7. Competing narratives, secrecy, and political agendas in the record

The documents reveal competing imperatives: U.S. strategic secrecy and the operational logic of SAC airborne alerts versus Danish domestic non‑nuclear policy and later parliamentary demands for guarantees; the Archive’s release aims to illuminate these tensions while some official U.S. histories had redactions that critics called excessive ^{[5] [9] [6]}.

8. Limits of the Archive sample and remaining gaps

While the Archive provides a suite of pivotal documents—1951 Technical Schedule, accident messages, State Department memoranda, and the two‑part briefing book—that together reveal planning and deployments at Thule through 1968, not every operational log or warhead inventory is public in these releases; the record as published by the Archive is extensive but not necessarily exhaustive ^{[1] [2] [3] [4]}.