>>17760024 (OP)>>17760025The US progressively -- first gradually and then all at once -- supplanted the British Empire as the dominant hegemon of the capitalist world-system. And indeed far surpassed it in sheer degree of hegemony within that system, attaining the status of what some refer to as "hyperpower."
Maintaining that power requires, among other things, a willingness to engage in acts of overwhelming force against any entity that is regarded as posing a threat to its hegemony or the composition of that world-system, regardless of how arbitrary and disproportionate the use of force is or how negligible the ostensible threat is.
Vietnam, for example, was itself never going to topple the US's preeminence or the security of the world-system, but its war of national unification in opposition to a colonial puppet regime in the south allied with the US was regarded as demonstrating a challenge to the credibility of the Truman doctrine (the ideological edifice of US hegemony at the time), and so the US was willing to use overwhelming force to at least maintain the pretense of its credibility.
The same is true today with regard to punitive economic sanctions ("maximum pressure" economic warfare against a civilian population) and regime change efforts (above sanctions, supporting terrorist groups, invasion) against Syria, North Korea, Venezuela, and Iran today.