In the period of about 10 years before the strike, Song under Wang's greedy reform policy Balanced Delivery Law had been constantly surpressing tribal people in the border, forcing their frontier local merchants to sell goods with low price (Song depended on Southern kingdoms for a lot of goods). Many tribal people lost everything and became literal bandits wandered into Dai Viet's territory seeking our protection. Dai Viet's envoys had been discussing this matter with Song many times and sent gifts to China to make up for their skirmishes, however Wang keep pushing for militarization and stopped all border trade. When we were notified of your dirty little plan to stock troops and attack us, we striked. Never gone past the territories without military fortification pointed at Dai Viet. Sneak attack ain't gonna work now!
Oh and the "destroy all our industries" is a lie that you pinkies used again and again. CCP attacked Lang Son and Cao Bang, they are the most remote northern border provinces with similar economic composition to the era of Viet-Song war- non essentials. CCP while retreating destroyed some railway sections that lead to China (lol thanks), sparse electrical system, residential houses and some small local mining infrastructure. And you know what little pink? We legitimately took over Chinese businesses in Saigon, sold the Chinese ethnics back to China for a good price and forced hundred of thousands of your people out of the countries to be raped and tortured by Thai pirates, ending Chinese merchants' dominance over South Vietnam since the start of Nguyen dynasty. But this ain't a competition to see who made Chinese people suffered more, right little pinkie? Because pinkies care about China and Chinese people, and would not want to attack a country Chinese people love operating their business in.
CCP invited our chief, not the other way around. Seems like China wont dare to attack us any time soon while we consolidate our power and economic relationships with western partners. Good business, thanks for the good trip