I am assuming first of all that the questioner meant ISIS... If not, then forgive me, because this response will be inapplicable.
ISIS stands for the Islamic State of Iraq and Syria. They hold to an extreme form of radical Islam. But what's more, they kill anyone who will not become ISIS. Not just who won't convert to Islam, but who won't join them in their terrorist overtake of the Middle East.
ISIS is incredibly brutal. If we thought Hitler and Stalin were ogres for their cruelty, ISIS is far worse. They systematically go through the villages, looking for Christian homes. Then they take the children, some even as young as 4 or 5, and behead them if they will not renounce their faith. There are credible reports of actual, literal crucifixions of ISIS enemies. The brutality of ISIS is almost unparalleled in our time.
Somebody needs to stop the evil. The US has both superior man power and superior weapon power. We could take out their tanks no problem with our air force, and make sure that ISIS is no longer a threat to the world.
Furthermore, ISIS is most definitely a threat to US national security. So yes, we should go all in to take out ISIS. It wouldn't have to be a long fight (speaking in war terms, probably a few months to a year), and we would be doing the world a big favor.
Just because you speak english dosent mean that you have to kill everyone who dosent. Im sure the people beheaded deserved it and provoked the doing. They probably didnt co-opperate with the ISIS leaders. I dont blame ISIS at all for what they did. If anything we should help ISIS.
As most people know, the US uses drone technology to destroy key ISIS points. There has been plenty of innocent people caught in those drone strikes. I mean, sure the US could "get rid" of ISIS completely but probably kill hundreds of innocent people along the way. In the end, ISIS will be struggling and probably use innocent people as their protection. Lastly, ISIS is just a name. The radicals don't change, but the name can. I think the US needs to focus on radicals as a whole rather than their name. I think the question needs to be restated as: Should the US focus on killing radicals in the middle east?
ISIS is a group of PATHETIC radicals who are a continuation or splinter faction of the has-been al-Qaeda. All we have to do is let them exercise their dominion over their own people until someone decides "Let's have some fun" and hires some private military contractors to take over the place.
America is a house divided against itself. It can barely sustain it's economy, it can't get the two factions within it to agree upon anything, and partisanship and threats have led the people to become either A. More well-armed than ever, or B. More nasty and hateful than ever. I do not think, from the standpoint of reason alone, that we can afford another war, let alone win it.
America's time as a superpower is up unless we do something to "clean house." There are bigger enemies than ISIS at play now. The war on terror has failed, but the war on American freedoms has run us down to the final straw.