under the guise of war
There's no guise. This is the way war has been prosecuted for millennia. The Geneva Convention, UNHRC, etc. are blips. War is genocide and always has been. Only in the late modern to post-modern era has war been something other than the complete annihilation of your enemies and their culture, including all the infanticide and rape that implies. If you're, for instance, the US prosecuting a war for nebulous geopolitical reasons, then you can slap up a veneer of rules and conduct. If it's a war of territorial expansion, on the other hand, you'd better be prepared to do what it takes to stamp out any trace of the people who originally lived there, or at least leave those who remain so broken and disempowered that they'll never pose a threat.
Expect more like Ukraine & Palestine as the US's grip on hegemony slips, and as we continue to slowly forget the lessons of the World Wars.