Being part of p5 has nothing to do with it. China just doesn't want to interfere in other countries business and they see how costly it's for the United states misadventures but as u said china still wield it's influence around in Myanmar and many other places.its just normal being a great power. The leaders today are more wise and just want to do business but I say Mao was better at dealing with foreign forces and make their lives a living hell just ask the Soviet in Afghanistan. Chinese weapons were flowing there through xinjiang in mass and US involvement in Vietnam.