Sigint Liaison with the Russians

After the German invasion of Russia in June 1941 a military mission (No 30 UK Military Mission) was sent to Moscow and learned that the Russians had a Y Service. In August, 1941 a Y officer from the Middle East went to Moscow. He was given little information, and wasn't allowed to see anything of the Soviet organisation. However, as British relations with the USSR had been bad for many years this was considered unsurprising, and in October 1941 the War Office on its own initiative attached an Army officer (who had been working as a Sigint traffic analyst) in 30 Mission. At the same time the Admiralty negotiated permission to build a Naval Y Station in the far north aimed at providing early warning of any attack on the convoys planned to bring supplies to the Russians. On the Army and Air Force side it was hoped principally to obtain Russian-intercepted German traffic and some help if possible on Japanese systems. In fact, apart from the supposition that Russian Sigint would be less efficient than British there wasn't any clear policy, other than that allied intelligence liaison was a "good thing". 

The Admiralty received Soviet permission to erect a Y Station at Polyarnii, near Murmansk, and British permission to give the Soviets information about Auka (a low-grade Luftwaffe system), and, in May 1942, sent a naval officer from GC&CS to Murmansk to arrange for the exchange of Naval and TA intelligence. As a result of this some naval intercepted traffic reached GC&CS and there was also an interchange of DF bearings.

The War Office representative also made some progress. He was authorised in February 1942 to train the Russians to break the German police ciphers which were being used in rear areas on the Russian front, as well as showing them some traffic intercepted in the UK. (It was never the intention that British success against Enigma should be revealed.) He reported that this had produced a favourable reaction and he asked to be allowed to expand the exchange, giving the Russians identities recovered from callsign analysis of certain German stations in return for traffic intercepted in Russia. In June 1942 he was recalled for discussion of policy and went back to Moscow as representative, not of the War Office, but of the Y Board. But the mood in Moscow had changed: the Russians stalled and eventually in November the Head of the Soviet Army section dealing with Traffic Analysis suggested that cooperation should be discontinued.

Naval cooperation in the far north continued on a restricted basis, though some intercepted material inaudible elsewhere did reach the UK. This lasted until spring 1943 when, just as the UK staff were preparing to hand over another batch of Y material, the Russians suddenly entered the British site, sealed up the transmitters and took away the "meaconing" apparatus (a means of falsifying German Beacon transmissions.) At the same time it came to British knowledge that the German Y Service was reading some high echelon Russian cipher systems without much difficulty. Convoys were not actually in operation at this time, but were expected to resume and the closure of the station and Soviet insecurity greatly increased the hazards of running them.

In return for German Police material, the UK had given the Soviet military the Japanese Military Attaché code, the "Bird book" and index (the GC&CS process for breaking out German enciphered callsigns), the solution to German aerodrome serviceability reports, the process for recovering German police keys, Auka, and some ISOS keys. The Russians had also been made aware that the UK could read the Army tank code, Army medium grade field ciphers as well as the cipher used by one of the German sabotage units. The UK side decided that unless and until the Russians resumed cooperation, no further material should be sent. There was no point in keeping a representative in Moscow and the liaison officer, while retaining the title 'Russian Liaison Officer', was relocated to GC&CS. GC&CS had only one vote on the Y Board but it was a significant one. its attitude towards Russian cooperation was becoming more assertive and more reluctant. 'Jumbo' Travis wrote to Heads of Sections in May 1943 saying that he was prepared to consider an exchange, but only if there was a solid return "as I am not now a believer in Russian cooperation".

Although it had been decided that the Y Board should have no representative in Moscow, 'C' felt that an SIS liaison officer might usefully represent Sigint as well. One went to Moscow in the summer of 1943, just in time for several things to happen all at once. The Soviets asked for a full description of the German Enigma machine; they captured a copy of Auka themselves; and German Y Service traffic intercepted by the UK revealed that Russian ciphers were still being read by the Germans.

A meeting took place in summer 1943 after the British Ambassador made representations to Molotov, and it became clear that the Soviets' main interest was to find out what exactly what the British evidence of Russian cipher insecurity was. They were told that the information had come from a disaffected Austrian prisoner of war and from information from Japanese Military Attaché decrypts; they were also told that the UK side would give no further Sigint-derived information until the Russians delivered on their promises of the previous year. There were a few sporadic meetings and it became perfectly clear in spite of the SIS representative's attempts to put the best possible interpretation on what was going on, that the Russians were trying to get what they could from the British without giving anything away themselves. Telegrams continued to pass desultorily throughout 1944 and an Enigma machine and a small amount of very low level Y information was sent, though probably more for SIS's benefit than for Sigint's. Before the end of the war cooperation had ceased.

Why were the Soviets so reluctant to carry out an exchange of material? GCHQ believed post-war that the Soviet Sigint organisation had made the authorities in Moscow aware that the material being offered by the UK was low grade and that therefore either the UK was keeping its aces up its sleeve, or it didn’t have any capability worth wasting Soviet time on.

In my last post I told the story of how some information derived from Enigma decrypts had been published after having been passed by military censors. Commenting on Twitter @jock_bruce said that "in that story the point is that the folk clearing stuff for publication need to know what they’re actually protecting". I think that there is a similar issue here: those making decisions – the single services, and subsequently the Y Board – didn't understand that any half-way competent Sigint organisation would realise that valuable information was being withheld.

Sigint liaison worked with the French and the Poles when there was a full exchange of knowledge between the national Sigint organisations of each country, and subsequently worked with the US and Australia, Canada and New Zealand, because there was full sharing and integration of staff in each other's organisations. It couldn't work if the exchange was partial and low-level, and it certainly wouldn't work if non-Sigint personnel were representing Sigint.