What differentiates ISIS from a terrorist group such as al-Qaeda is that their goals are geographically localized. In this regard, a more apt comparison might be with the Taliban. As we know, al-Qaeda was able to operate in Afghanistan because the Taliban were in power, and sanctioned their presence. If ISIS were to succeed in establishing an Islamic caliphate, there is a real risk that they would offer safe harbor to terrorist groups with similar beliefs but more global goals, thus providing a place to plan and train for attacks around the world.
In the face of such a threat, the United States should make a concerted effort to counter ISIS. Sending military advisers to aid in intelligence analysis and strategic planning is the preliminary stage of US involvement in this conflict. If the advisers are able to aid in identifying opposition targets, US airstrikes should be used to give Iraqi security forces assistance in retaking territory.
Diplomatically, the United States should encourage the government of Iraqi Kurdistan to take a leading military role against ISIS. If encouragement does not suffice, there are other opportunities to entice the Kurdistan Regional Government by relaxing restrictions on the sales of oil that originates from the region and access to additional oil fields.
Generally speaking, the emergence of ISIS has posed a significant security threat to regional and international states alike; a threat which challenges the stability and territorial integrity of regional states as well as Western regional interests. As known from International Relations and particularly Realism literature, (mutual) security threats are one of the most important factors in the formation of different kinds of alliances. As such, it is without surprise that we see unlike partnerships to emerge, such as the ones mentioned below.