I do not shy away from the idea that occasionally military conflicts are inevitable or capable ways to quickly resolve dangerous international situations. But ISIS doesn't strike me as a problem that we can resolve in this way with military force. It is unclear to me what our goals are in intervention. It is unclear to me why our forces, or our interests are of higher concern than those of the regional players who may be threatened (Saudi Arabia, Iran) that we should react or act on their behalf, or why we should seek to prevent those regional players from acting and reacting (Iran), and it is pretty clear that we (the US/EU) are not actually threatened that we need to respond directly and promptly ourselves.
The threat of "hundreds of members who hold Western passports" does not materialize to me as a conceptual threat that these members could turn around and conduct terrorist attacks on American or European soil with relative ease. Conducting and plotting terrorist attacks is difficult to carry off successfully. And more to the point, if we're aware they have these members, these individuals can be flagged as potentially dangerous and monitored and observed well before they could carry out any plot that is made. That's precisely why we have an NSA or CIA or FBI or MI-6, etc (it isn't for monitoring hundreds of millions of unsuspecting American citizens, but for monitoring much more suspicious potential threats like this, western pro-Islamist radicals willing to go train or fight in foreign insurgencies).
This is also one of the reasons most of the intelligence community doesn't appear to agree with the emerging public consensus that ISIS represents an imminent terrorist threat to Americans over the next several years. It can declare it wants to attack Americans or Brits all it wants, but actually doing it is very different from proclaiming itself to be hostile. That's mostly a PR stunt to attempt to recruit, not a statement of an ongoing mission planned and prepared. Al Qaeda was able to carry off its attacks over a decade ago largely because it had a long timeline to develop them and intelligence community coordination was poor in reaction or response. I'm not persuaded our intelligence community has learned much about how it should conduct its operations to identify potential terrorism threats, but it's possible that a rather public threat like this would command sufficient attention to be identifiable in the wake of the knowledge of what such threats could maybe eventually lead toward (eg, 9-11). This intelligence operation should be the focal point of any response to the idea that Americans might be endangered now or in the future, and not open-ended military campaigns conducted abroad in intractable political contests over power and religion in other countries.
In general, ISIS lacks power projection capabilities common to a large developed nation-state. It doesn't have an air force, navy, long-range missile capabilities. It largely consists of well-armed guerrilla and insurgent infantry forces (similar to the Taliban in Afghanistan). It will as a result have difficulty expanding, consolidating, and enforcing rule over areas of the Middle East that it does not already enjoy, for various sectarian religious and political reasons, a modest level of public support. That is to say: if it tries to expand or attack or agitate in areas that aren't mostly Sunni, and mostly irritated with Western or "pro-Western" governments, it won't get much done and will be resisted by any capable forces available. It can be an irritant in that area and represents a threat to the region and its relative stability (such as there is any), but it cannot control much of significant importance to American interests. People invoking Chamberlain "appeasement" and Godwin's Law comparisons have no idea what they are talking about and should be ignored. Germany was a powerful nation-state with a capable military for power projection and a burgeoning economy to support that machinery of war in the 1930s. ISIS is none of those things, and probably never will be (this was also true of the Iraqi state in the early 2000s). Such talk needs to be silenced and ignored as patently idiotic. What it can do is be annoying, and perhaps try to operate as a zone to attract and train militant fighters and/or terrorists. But it can't represent a major threat to American interests and safety. It bears keeping an eye on, not a preemptive military strike.
Bombing insurgents, or sending in special operations teams, might help in small doses where our regional allies require assistance, but the main line of resistance needs to be coordinated and conducted by those regional allies (Jordan, Kurds, Turkey), and by other regional players who might be endangered in some way (Saudi Arabia, Iraq, Iran, Syria). They are the ones threatened by direct attack or occupation and in need of response to overturn the danger. If it were clear that our intervention was to buy time for these disparate entities to coordinate or develop a strategy to respond and crush this rebellious force militarily and also provide some political means of responding to the situations that allowed it to flourish (local repression by Syrian and Iraqi governments primarily), then perhaps such interventions over a brief time could be warranted. I am skeptical that the local powers can coordinate politically and militarily; (Iran and Saudi Arabia seem to hate each other for example. And as a result skeptical that they can respond to the political problems involved; Iraq and Syria were in some measure the cause of those problems, it seems unlikely they can help solve them. This situation will not be best resolved with a semi-permanent force of US power tied to the area with the need for bombings and assassinations.
Our interventions thereby exist in a strategic no-man's land. Since we are responsible in some measure for the political situation in Iraq, it seems unlikely we can help much on that front either. Interjecting ourselves into civil wars and sectarian strife with an intent to resolve them is unlikely to be a fair long-term use of our power and capabilities. This has been borne out in Israel-Palestine for decades, in Palestine internally for a decade, in the Iran-Saudi Arabia proxy conflict that we have allowed ourselves to be dragged into rather than selecting a sensible set of allies, ideally who share western values in some measure, to support ahead of time as a means of protecting and expanding our hegemonic power through soft and hard power projection, and so on. It is extremely unlikely that a campaign of bombing, or special operations, or military occupation, will successfully repress and destroy our purported enemy on its own without an overall COIN strategy that our allies can successfully execute to defuse the intractable political and sectarian conflicts that have brought this to our attention. Which leaves the prospect of intervention open-ended, without a position and goal of success to achieve that allows us to leave the situation behind at some future date. Given that we have had a history of this as well (Iraq under Hussein, Afghanistan under the Taliban/Karzai), this should tell us that this strategy lacks a degree of wisdom and smacks too much of a reaction to emotion rather than a reaction to a threat of grave concern.
Correction Of The Day
17 minutes ago