If some other nation had clandestine organizations working US soil to capture or eliminate citizens or legal foreign nations on belief they were criminals or security threats, would the US view this organization as criminal or terrorist?

The CIA and Navy Seal Team 6 on the surface would seem to be outside of US justice and oversight. They, like the Blackwater operatives have conducted questionable killings and lose of liberty of private citizens. I am quite sure in many cases they by passed getting the blessing of the governments in whose nations they were operating in. If some nation sneaked operatives into the US to capture and ferret out of the nation to stand trial in their home country or simply assassinated them, would the US see them as terrorist or criminals killing US citizen, or view them as patriots trying to do what is in the best interest of their nation? If they are looked at as terrorist or criminals, how does the US doing the same to them not criminal or an act of terrorism?