Mao Zedong moves to Wuhan , Lin Biao to Suzhou and the general staff to a nuclear bombproof bunker in the western hills outside Beijing. The country's warplanes are scattered around northern China, runways at the main airports blocked and workers given weapons to shoot Soviet airmen when they land.

It is October 1969: China is preparing for a nuclear attack by the Soviet Union. Lin, second to Mao, orders 940,000 soldiers, 4,000 planes and 600 vessels to scatter from their bases and the transfer of major archives from Beijing to the southwest.

Then US president Richard Nixon intervenes. Secretary of state Henry Kissinger tells the Soviet ambassador in Washington that as soon as the Soviets set off their first missile against China, the US will launch nuclear missiles at 130 Soviet cities.

This is the dramatic account in an official magazine of the closest China has come to a nuclear war. The latest issue of Historical Reference, published by the People's Daily, mouthpiece of the Communist Party, describes in detail the five occasions in the post-1949 period when China was threatened by nuclear attack.

It is a rare account by an official publication of the most dangerous moments of the People's Republic. They are a far cry from the nuclear security summit in mid-April in Washington, where President Hu Jintao was received as an honoured guest and key interlocutor.

Of the five nuclear threats, four came from the United States and one from the Soviet Union.

The most serious came in 1969 after military clashes in March on Zhenbao Island - Damansky in Russian - on the Ussuri River, Heilongjiang , that marks the border in China's northeast. On March 2, Chinese troops ambushed Soviet border guards; they retaliated on March 15 by bombarding Chinese military concentrations and storming the island. According to Chinese figures, 58 Soviets were killed and 97 injured.