The practice of using codewords for SIGINT reports and other SIGINT material derived from the World War II use of the word “ULTRA” to mark the product of high-level cryptanalysis. Codewords were selected by agreement among the international partners.
In the period after World War II, for security reasons, the SIGINT system changed codewords annually. Within a few years the period between changes began lengthening, first to a biennial basis, then longer; the expense and trouble of changing rubber stamps and preprinted paper had begun to tell. The codewords TRINE, SAVIN, and LARUM were compromised with the North Korean capture of the collection ship PUEBLO in January 1968 and were displayed in various public media. The final change of codewords came in December 1968, to UMBRA, SPOKE, and MORAY.
Source: NSA.gov
TOP SECRET//SQUIRREL was NOT a codeword.
Listed below are codewords used for Top Secret COMINT reporting.
ULTRA (194? – Mar 1946)
CREAM (Mar 15 1946 – Sep 1947)
GLINT (Sep 1 1947 – Jun 1949)
COPSE (Jul 1 1949 – Aug 1950)
ACORN (Aug 1 1950 – Jun 1951)
SUEDE (Jul 1 1951 – Jun 1952)
CANOE (Jul 1 1952 – Sep 1953)
FROTH (Oct 1 1953 – Dec 1954)
EIDER (Jan 1 1955 – Jun 1959)
DAUNT (Jul 1 1959 – Dec 1960)
DINAR (Jan 1 1961 – Sep 1965)
TRINE (Sep 1 1965 – Dec 1968)
UMBRA (Dec 1 1968 – Oct 1999)
Station HYPO 
10 September 2020 at 11:23
The last 2 will be forever enshrined in my mind
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10 September 2020 at 11:46
Always interesting to read your posts, thanks and hope all is well.
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10 September 2020 at 15:12
As the saying goes: ‘Those were the days’ – for the last 5 for me that is – and SAVIN and LARUM were also in there as
well. Others lurk in the shadows too. Thank you again, Mario, for the history lesson. Have a great day and stay safe.
Jim
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10 September 2020 at 15:46
In the late 70’s a bunch of us were drinking in the barracks and started going through the phonetic alphabet (don’t ask me why) and when we got to the letter U someone yelled out Umbra. We were all CT’s and everything stopped; we all just looked at the guy in shock, finally someone said Victor and we never “SPOKE” of it again. LOL, good times.
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10 September 2020 at 17:18
Hanna Barbera cartoon series: Secret Squirrel and Morocco Mole
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10 September 2020 at 19:39
I don’t think I’ve ever uttered it aloud outside of secure spaces in the last 51 years. I don’t think I’ve ever written it in the clear. Never had occasion to experience the first 12. The same is true of the other two lesser classifications.
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10 September 2020 at 19:49
I don’t wish to get off color here but since we’re on the subject. I remember the penalties if we got caught mishandling classified info in any way. Fort Leavenworth prison didn’t sound to inviting. Yet certain members of our government seem to get away with it w/o any form of punishment…not to mention any specific names
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10 September 2020 at 20:05
I thought “DINAR” was compromised by SECDEF McNamara when he once brought out a folder of messages in a televised interview with the President. I heard that one of the messages was sticking out, and “Top Secret DINAR” was clearly visible. I always remember one day when my brother (who served before me as a CTI) once teased me saying that i worked with Top Secret “DINAR” messages. I did not respond not wanting to reveal that “TRINE” was the new code word. That night, on the History channel, there was a story about some kind of submarine having problems. At the dock, a sailor was shown displaying messages the sub contained, and in plain daylight, one of the messages had “Top Secret Trine” stamped on it. I knew then, that “TRINE” was declassified. I was in the Navy when the Pueblo was captured, but we still used TRINE (I left in September, 1968). In December, after the crew was released (in November), TRINE was dropped
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