More historically apt US had plans to annex British Canada when Canada was British proxy that threatened US security. Canada only coexisted with US when Britain

More historically apt US had plans to annex British Canada when Canada was British proxy that threatened US security. Canada only coexisted with US when Britain conceded influence over Canada which was forced to become geopolitically aligned to US. Extrapolate to RU/URK, PRC/TW. Big countries want their neighbours either aligned or toothless buffer states.