If united States attack North Korea, I sure world war 3 is beginning, China will attack united States and then Europe will help USA.
Why would the Chinese attack the Americans? This is nonsense. China is not friendly with North Korea and Kim is a strategic partner of China. America largely supports and develops the economy of China. I am sure that the Chinese support the Americans, but try to negotiate with Trump not to restrict us investment in China.
I agree, they will rather agree than they will fight. This is unprofitable for their continued productive cooperation.