Defending meaning need to over run the cambodia capital and control for whole 9 years? You vietnamese really know how to use beautiful words to mask your ambition.China copy what Britain imperial did in the past.
Vietnam has simply defended counter attack of Khmer Rouge, backed by China. Laos and Cambodia is independent state now. Why China has diplomacy relation with Laos Cam ,"colonies" of Vietnam. ?
There is no such thing call copy what superpower do. All superpower needs to its flex muscle to let small but igorant country to know who is the real superpower.
Vietnam is weak and no money, Cambodia and Laos choose China now.