I understand perfectly what you're saying, but in order to avoid any Constitutional conflicts, war could be declared on a country (or countries) and ALL their people could be ejected from the US.
Gitmo is a perfect example. Had we declared war, those men would have been enemy combatants, and could have been treated as such. Instead, they were treated as civilians in temporary custody with all their human rights intact.
I'm not saying islam isn't a problem, and I'm not saying ISIS and other such groups shouldn't be dealt with, but creating more problems by going about it wrong is not the answer.
Just my 2 cents.
As for the Gitmo prisoners, weren't they initially, and properly, classified as 'illegal combatants' rather than as 'civilians.' With very different, and very fewer, rights. Because they were fighting without uniforms and hiding amongst the civilian population, the international laws of war, developed to try to minimize harm to noncombatant civilians when large armies were roaming Europe, didn't protect them. Their behavior put noncombatant civilians at risk because the legal combatants had to be able to defend themselves and couldn't differentiate the bad guys from the innocent. They were liable to be shot on capture, like spies and pirates, IIRC. I'm not sure they are still liable to be shot after a decade in custody, though for this bunch shooting them would be preferable to releasing them to shoot at us! IIRC, had there been a formal war declared and they still continued to fight without uniforms admixed with the truly civilian population they'd still be 'illegal' combatants. Cf. old war movies when our guys say they could be shot if caught out of uniform, or the Battle of the Bulge when German's were executed for impersonating Americans. War, vs. something less than war, as a response to aggression needs to be fit to the circumstances. Declaring war places various restrictions on ourselves and is overkill for some circumstances. I can hope circumstances call for leaving the 'war' option on the table, but don't leave it artificially off the table.