The US is the hegemonic imperial core country (like the UK before it) and has been since the end of WWII, and even moreso since the end of Cold War I. The imperial core’s imperialism is driven by the monopoly stage of capitalism. The imperial core has been pillaging the Global South for the last 200+ years, including putting China through a century of humiliation. It caused WWI & WWII & Cold War I, and has now started Cold War II.