the traditional superior–inferior relationship between the two coun-
tries; and more practically they knew that only the Soviet Union could
provide the quantities of aid necessary to reconstruct their war-damaged
country. Soviet aid was already propping up Laos, whose economy had
virtually collapsed. In mid-1977 Vietnam cemented its position in Laos
by signing a twenty-five-year Treaty of Friendship and Cooperation. For
Hanoi, its ‘special relationship’ with Laos served as a model for relations
with Cambodia, but it was not one the Khmer Rouge were prepared to
accept.^2 Faced with increasing Cambodian truculence, Hanoi held
Beijing responsible and strengthened ties with Moscow.
From mid-1977, relations between Cambodia and Vietnam
rapidly unravelled. Fighting escalated along their common border
until, in December, Vietnam retaliated in force. Phnom Penh
promptly broke diplomatic relations with Hanoi. Beijing made some
attempt to moderate the provocations of the Khmer Rouge, but to
little effect. Meanwhile relations between China and Vietnam also
deteriorated over Vietnamese treatment of ethnic Chinese. In south-
ern Vietnam, Chinese were targeted as class enemies and sent to farm
the New Economic Zones. In the north, Hanoi began expelling
Chinese from provinces bordering the PRC. In the end as many as
200 000 were forced to leave, many evacuated on Chinese vessels.^3 By
mid-1978 China had concluded that Vietnam was no longer open to
reason and was determined to use the Soviet Union in order to pursue
its ‘regional hegemonist’ ambitions, to the detriment of the PRC. In
fact, Vietnam had decided that it was in an impossible situation. With
border provocations escalating both north and south, Hanoi believed
its only recourse was to overthrow the Khmer Rouge regime in Cam-
bodia. In November 1978, Vietnam signed a Treaty of Friendship and
Cooperation with the Soviet Union, a clause of which called for
immediate consultations in the event that either was ‘attacked or
threatened with attack...with a view to eliminating that threat’.^4
The following month, the PRC and the United States agreed to nor-
malise relations. Ten days later Vietnam invaded Cambodia.
A Short History of China and Southeast Asia