Expert witness Stephen Morris offered a nuanced view of the Cambodian-Vietnamese conflict during the Khmer Rouge era yesterday, reiterating his belief that Vietnam intended to control the Cambodian communist movement, but also noting that Cambodian forces antagonised the Vietnamese prior to the 1979 invasion.

Khmer Rouge leaders Nuon Chea and Khieu Samphan are on trial for various crimes against humanity, including genocide against the Vietnamese, as well as internal purging of their own officers. Defence teams have long argued that the purges were a reaction to a legitimate attempt by Vietnam to overthrow the Cambodian government.

While Morris once again testified yesterday that the Vietnamese had hoped to control communism in Indochina in the 1970s, he also maintained that the Khmer Rouge purges had largely targeted loyal party members.

“The Vietnamese set up Cambodian communist structures, which they tried to dominate with their own Khmer Viet Minh agents, but Pol Pot and other leaders were aware of this strategy,” Morris said.

By around 1975, the researcher continued, almost all of these Vietnamese agents had already been removed from power.

“The purges and terror campaigns which took place after 1975 branded people who were loyal members of the system,” Morris said, calling Pol Pot “paranoid” and accusing him of conducting a “campaign of terror within party leadership”.

Morris, who was granted unprecedented access to archives of Soviet communications with Hanoi, testified that Vietnamese communists had hoped Nuon Chea would help overthrow the Khmer Rouge, with Vietnamese General Secretary Le Duan going so far as to refer to him as “our man” and a “personal friend”.

However, Morris said, these hopes were “groundless”.

Morris also testified that Vietnam had a far superior military and could have easily crushed the Khmer Rouge much earlier than 1979, but instead tried to negotiate with the regime, even while Khmer Rouge soldiers were slaughtering Vietnamese civilians.

Communications from the same Soviet archives between Le Duan and the Soviet ambassador seem to confirm this desire.

In October 1977 – just two weeks after a Cambodian raid into Vietnamese territory – Le Duan noted that Vietnam had the capability to “rout” Khmer Rouge forces, but that their response was to display patience and attempt to find a peaceful resolution.

Morris also said that one of the primary reasons Vietnam did not invade Cambodia earlier is because it was “impossible politically”.

When they finally did take Phnom Penh in 1979, he added, Vietnam went far beyond what the international community desired.

“Vietnam didn’t simply overthrow the regime; they occupied the country for 10 years and tried to create a regime in their own image in Cambodia.”