The only logical means for the Chinese and North Koreans being able to invade another country would be this.
Deep in the Himayalas, secret underground aircraft hangars housing thousands of 4 engine cargo planes and tactical fighter aircraft would be used to transport manpower and material hundreds of miles to their targets. They could roll Taiwan, Japan, Philippines, Malayasia, Eastern Siberia, South Korea and Northern Australia inside of 24 hours with coordinated attacks via aircraft and paratroopers.
The single Chinese aircraft carrier would be steaming all over South China Sea launching coastal attacks with the help of the Asian Pirate gangs and being able to deny US aircraft carriers from entering the same waters.
In reality, they could never sustain the ability to handle all of that for more than 2 months. Our B-2s and F-117's would continually take out Chinese and North Korean targets every night. B-52 raids would shell shock so many that white flags would pop up so quickly. Once the USMC showed up, all resistance would be futile.
Just enjoy the film for the sure entertainment of a what if scenario happened.
Until the Chinese develop sharks with lazer beams, I think we will be safe,