What did the declassified documents reveal?

This is a declassified Central Intelligence Agency photographic intelligence report on a suspect signals intelligence facility at Chih‑kan, China, dated October 1967. The document is notable because it provides a rare visual and technical description of a Cold War era communications installation that U.S. analysts believed could be linked to foreign intelligence activities in the region. The record was made publicly available through The Black Vault, an online archive that publishes declassified U.S. government documents. The release is part of a broader effort to provide public access to historical intelligence assessments. The document bears a declassification review notation from the National Imagery and Mapping Agency and the Department of Defense, indicating that it was cleared for public dissemination after a standard review process. The report reads as follows: CHIH‑KAN SUSPECT SIGINT FACILITY CHINA OCTOBER 1967 Copy 1 of 2 pages. Declassification review by N-I-M-A slash D-O-D, Group 25X1. Excluded from automatic down‑grade and declassification. Approved for release. National Photographic Interpretation Center Function. HF/DF Installation Name: Chih‑kan Suspect SIGINT Facility. Location: approximately three nautical miles west‑north‑west of Chih‑kan. Map reference: ACIC series, scale one to two hundred thousand, NPIC (TS 25X1, 25X1D). Basic operational components: one thick eight antenna, RF; two horizontal dipole antennas, each approximately twenty‑five by one. Imagery analysis: The HF communications facility is three‑tenths nautical miles east of the thick eight facility and consists of two horizontal dipole antennas, each approximately twenty‑five by one. Based on map data only, the approximate azimuths of dipole antenna one are ninety degrees and two hundred seventy degrees, and of dipole antenna two are one hundred fifty‑five degrees and three hundred thirty‑five degrees. The possible correspondents or spies associated with these antennas are Hanoi, North Vietnam, and Nan‑ning, China. There is also a suspect SIGINT facility at Nan‑ning. Approved for release. Earthen fence. HF/DF facility. Chih‑kan thick eight. Communication facility, Chih‑kan. End of document. The Black Vault notes that this record is a photographic intelligence report on a suspected signals intelligence facility in Chih‑kan, China, dated October 1967, and that it illustrates the type of technical analysis performed by U.S. intelligence agencies during the Cold War. This is what the public record looks like at its most ordinary. For the full document, visit storyflo.com and the archive at archive.org, where the record is available at the canonical URL https://archive.org/download/us-china-intel-CI01835/CI01835djvu.txt.

Why was this case declassified?

This material entered the public record through the U.S. declassification and Freedom of Information Act (FOIA) process. The originating source document is linked on this page so the citation chain is auditable.

Central Intelligence Agency Photographic Intelligence Report On A Suspect

◆ BLUF — The short version

This is a declassified Central Intelligence Agency photographic intelligence report on a suspect signals intelligence facility at Chih‑kan, China, dated October 1967. S. analysts believed could be linked to foreign intelligence activities in the region. S. government documents. The release is part of a broader effort to provide public access to historical intelligence assessments.

Date: AUG 13 · 2026
Release: Declassified · U.S. public record (FOIA)
Source document: View the primary source document

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This is a declassified Central Intelligence Agency photographic intelligence report on a suspect signals intelligence facility at Chih‑kan, China, dated October 1967. The document is notable because it provides a rare visual and technical description of a Cold War era communications installation…

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Questions about this case

What was Central Intelligence Agency Photographic Intelligence Report On A Suspect about?: This is a declassified Central Intelligence Agency photographic intelligence report on a suspect signals intelligence facility at Chih‑kan, China, dated October 1967. S. analysts believed could be linked to foreign intelligence activities in the region. S. government documents. The release is part of a broader effort to provide public access to historical intelligence assessments.
Why was this case declassified?: This material entered the public record through the U.S. declassification and Freedom of Information Act (FOIA) process. Storyflo narrates it directly from the public release.

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