I'm reading Jonathan Fenby's A History of Modern China and he mentions in passing that during the late 60s, Mao was very concerned about a soviet attack on China possibly including a nuclear strike on Beijing (the threat was considered serious enough to relocate some officials from the capital). Was there any basis to these concerns (e.g. misinterpreted intel etc) or was the idea just out of nowhere?
Thanks.
It wasn't unjustified at all. Chinese Soviet relations really degraded badly over the course of the Sino-Soviet split, and relations at some points reached such a nadir that conflict became likely, even culminating in several "minor border skirmishes" over key disagreements in various parts of the border line. The main issue was the huge length of the border shared: Such a long border was a challenge for both nations to defend, but especially so for the Soviets. Whereas the main large Chinese geopolitical and military opponent was the Soviet Union, the USSR had the twin requirements of protecting its Asian border from Chinese aggression, and also maintaining its enormous military bloc in Eastern Europe to ward off NATO.
The result of this was high Soviet anxiety over possible Chinese superiority in numbers in a potential Asian border conflict. Russia is big, and having to maintain an armed forces capable of holding both the Asian land border and block NATO in Western Europe is a big ask financially, even for the bloated military expenditure of the USSR. Geographic size means moving troops from one side of the Soviet Union to the other was not something that could be undertaken lightly. You see this concern reflected in Soviet military doctrine of the period: Flicking through Soviet manuals and tactical texts, you would be surprised to see so much emphasis was placed on defensive posture, when its main military goal of 1960 onward is a fast offensive push into Western Europe. Looking at the Chinese threat, this emphasis makes sense. You even see weapons being developed by Soviet bureaus with the express purpose of giving Soviet troops a firepower advantage at the small unit level against large numbers of attacking Chinese infantry, such as the AGS-17 grenade launcher. This suggests evidence of the Soviets taking lessons from the Chinese ""human wave"" tactics of the Korean war (although I use the term with the biggest air quotes I can find, as "Human Wave" is an incorrect gross simplification of Chinese infantry tactics in Korea, but I use it for ease of explanation, as this is what Soviet planners genuinely worried would occur).
But on to nuclear weapons. Seeing a potential conventional imbalance on its Asian border, the USSR sought to counteract this through redeployment of its nuclear arm over the course of the split: Pre-split, most of the Soviet land based missile arsenal was located in Western Russia, deployed against NATO tactical and strategic targets in Europe. Souring Sino-Soviet relations saw a large scale redeployment, at first consisting of older weapons, to new silos and launch sites closer to its Asian border. Smaller intermediate range weapons gave the potential to address any conventional imbalance in forces, but the key deterrent threat was to Chinese cities. With the major Chinese population centers in range of even older generation and intermediate range weapons, it was enough to make Chinese leadership wary of provoking the USSR, who had correctly deduced that China had exactly the same reasons to be fearful of decapitation strikes against its captial city as the Soviet Union did: Large, rigidly centralized communist states, dependent on a small cabal of leaders and bureaucrats, do not react well to having their major leadership centers annihilated with little warning.
The Zhenbao (Damanski) Island clash in 1969 signified that Sino-Soviet relationship was tense, actually it seem they were on brink of war at the time.
Since China broke up with Soviet around 1960s and then even seeked to replace Soviet as "leader of world revolution", it was reasonable for Soviet to contain China (which is later proved in China-Vietnam war). To Chinese, a "surgical strike" on its nuclear forces seemed possible: China just tested hydrogen bomb in 1967, which is a serious threat, and it was the years of Cultural Revolution so China was in a weakened state. Mao's paranoid in his late years may fueled this, but the fear is still reasonable.
In fact, Soviet even informed US that they may want to conduct such a nuclear strike. I just found some compiled files and analysis on this:
http://nsarchive.gwu.edu/NSAEBB/NSAEBB49
This one especially, http://nsarchive.gwu.edu/NSAEBB/NSAEBB49/sino.sov.10.pdf
Boris Davydov , Second Secretary of Soviet Embassy, directly asked William Stearman how would US react if Soviet conduct a surgical strike on China.
P.S. What I found interesting is, in China there's a dominat view that in 1969, US helped stopped Soviet nuclear strike on China, "saving" China. It's so dominant that if you ask a question like this, the netizens will immediately tell you the story, with details like how a Chinese operator hanged up Kosygin, how Nixon answered Soviets with dead sure "that means WW3", and how Kissinger informed China brilliantly through a newspaper... But this story could be very false, as it was just popular on Chinese internet instead of among historians.
That been said, the story's author did said US leaked the information about possible Soviet attack though Washington Post on Aug 28th 1969, could anyone check that?