The Chinese especially still practice a form of irregular People's War, except the infiltration is now done by companies, universities, communities and expansion of Chinese economic influence. As the great Chinese reformer, Deng Xiaoping said himself: "it doesn't matter if the cat is black or white, as long as it catches the mouse."
Where force is needed they use civilians (eg their fishermen) backed up by paramilitary police forces.
The biggest component of this is One Belt One Road economic initiative whose plans basically involves turning huge chunks of Asia, middle East, Africa and Europe into essentially tributary states reliant on the Chinese for their economic life blood.
And unlike Chinese companies, western companies no longer work in the interest of western countries (indeed the CIA reported on this in the 1970s). Chinese companies work in conjunction with their government's interests (to not do so is to risk economic repercussions but also Chinese government understands guanxi networks which means Chinese business and government are in a symbiotic relationship).
The US and west aren't really equipped for this. They never have been and have always struggled with how to defeat irregular foes.
And this foe is ambitious and already wields huge power thanks to western neoliberalism, which shifted huge capital and most importantly productive capability to China. It can be argued that he who produces, rules the world. That was the case with Great Britain and USA. Now China has that power.
(And despite this being an age of the internet, the internet is still reliant on manufactured goods to exist).
All the stealth fighters, missiles, troops and drones in the world means precious little if you are unable and/or unwilling to use it and your opponent uses other non-traditional methods to gain power at your expense.
