The apparent beheading of American journalist James Foley by the Islamic State of Iraq and the Levant (ISIL) is a stark reminder of the group’s terrible brutality and the seriousness required to counter them. Unfortunately, much of the political discourse about the Islamic State of Iraq and the Levant (ISIL) is counterproductive to good policy. Many of the basic facts are wrong and the arguments—whatever the merits of the policies they prescribe—tend to be political, overly personal, and hyperbolized. President Obama’s policies in the Middle East have failed in numerous ways, but he is right that the paucity of our political debate is the greatest threat to our global standing.

One cannot credibly argue that the U.S. withdrawal from Iraq in 2010 contributed to the rise of ISIL without also acknowledging that the U.S. invasion in 2003 did the same. The former without the latter is a political argument, not a policy position. The same goes for airstrikes in Syria and arming the Syrian rebels. It’s a reasonable hypothesis that supporting the Free Syrian Army earlier might have blunted ISIL, but that’s a pretty hollow position if one also gives Syrian rebel factions a pass for tolerating and even embracing ISIL and Jabhat al-Nusrah through late 2012. As a long-time analyst of jihadism in the Middle East, it was clear to me in the summer of 2011 that the Islamic State of Iraq was well-positioned to capitalize on what was then a largely peaceful Syrian protest movement. And it was just as obvious that the group—whose brutality, extremism, and grandiose political aspirations were well-documented long before the Syrian uprising—would later turn on the Syrian rebels whose cause they claimed to champion. The same should have been obvious to the Syrian rebels, their external supporters, and pretty much anyone interested in the Syrian uprising and the overthrow of Bashar al-Assad.

Retired U.S. Army Col. Pete Mansoor is a serious man, but his assessment that the mission against ISIL will require 10,000-15,000 troops does not match up with the policy the President has chosen. Mansoor’s troop numbers are based on a policy “to roll back ISIL”, when the President has carefully limited his policy to “stopping the current advance” and aiding refugees. Reading most of the media coverage over the last few weeks, you’d be forgiven for thinking President Obama was seeking to defeat ISIL in detail, but had chosen ineffectual means. But that is not his goal, even considering the coordinated U.S., Iraqi, and Kurdish effort to retake the Mosul Dam from ISIL. It is fair to criticize the President’s policy as too limited or vague (I think it is both), but it is not to roll ISIL back and should not be measured on that basis. That distinction makes a difference, because as Doug Ollivant and Ken Pollack have both pointed out, airpower is much more effective against an army massing for an offensive than on troops settling in to govern in urban areas.

The larger problem with Mansoor’s vision is that “rolling back” ISIL is an unstable and untenable policy at this time. The Islamic State is a threat to U.S. interests because of the safe haven it creates and the instability it fosters; the exact location of its borders is not the most important factor. And so a policy of pushing them into a smaller box does not solve the problem; it is a temporary fix, an open-ended commitment, an invitation for mission creep, or all of the above. If destroying ISIL becomes the near-term policy goal—which seems the likely outcome of saying you are going to “roll back” the group—then 10,000-15,000 troops vastly understates the true commitment, which will actually require years, direct military action on both sides of the Iraq/Syria border, tens (if not hundreds) of billions of dollars, and many more than 15,000 troops. ISIL is an inherently resilient organization—look how far they have come since getting “rolled back” during the Surge in 2007 when 150,000 American troops were occupying the country.

One thing is clear about President Obama: right or wrong in his decisions, the guy does not want to be fed a bunch of bullshit. And many of the arguments made about ISIL, Syria, and Iraq these days are spurious —even when used to advance reasonable policy recommendations. The arguments to “roll back” ISIL fall into this category. Obama recognizes his critics are, intentionally and unintentionally, trying to back him into mission creep and he intends to avoid that outcome. As a result, he does less than he should (and maybe would) if he could manage the domestic politics and the U.S. Congress better. Whatever Obama’s mistakes, it is hard to blame him for being gun-shy politically after watching the Benghazi shenanigans for two years. If Obama’s political opponents talk impeachment over an incident like Benghazi, what would they say if U.S. weapons provisioned to Syrian rebels wound up in the hands of ISIL, as is almost certain to happen to some degree with a large scale weapons delivery program?

This is why politics should stop at the water’s edge: partisan tussling makes for bad national security policy and makes us less safe.

No one has offered a plausible strategy to defeat ISIL that does not include a major U.S. commitment on the ground and the renewal of functional governance on both sides of the Iraqi-Syrian border. And no one will, because none exists. But that has not prevented a slew of hacks and wonks from suggesting grandiose policy goals without paying serious attention to the costs of implementation and the fragility of the U.S. political consensus for achieving those goals. Although ISIL has some characteristics of a state now, it still has the resilience of an ideologically motivated terrorist organization that will survive and perhaps even thrive in the face of setbacks. We must never again make the mistake that we made in 2008, which was to assume that we have destroyed a jihadist organization because we have pushed it out of former safe-havens and inhibited its ability to hold territory. Bombing ISIL will not destroy it. Giving the Kurds sniper rifles or artillery will not destroy it. A new prime minister in Iraq will not destroy it.

Please do not step in here with the fly-paper argument: that the conflict will attract the world’s would-be jihadis to one geographic area where we can target them all and thereby solve the problem. Notice that no authorities on jihadism ever make this argument. That is because they understand that war makes the jihadist movement stronger, even in the face of major tactical and operational defeats. The conflicts in Syria and Iraq strengthen ISIL because war is the only force terrible enough to hold together a broad and extreme enough Sunni coalition to be amenable to ISIL. Abu Mus’ab al-Zarqawi recognized this in 2004 and built a strategy of provoking Shia militias in order to consolidate fearful Sunni groups. The concept was sound so far as brutal jihadi strategies go, but Zarqawi’s organization was just too weak relative to his opposition (U.S. troops and Shia militias) to execute it. Zarqawi picked a fight he could not win—provoking attacks on Sunnis without being able to defend them. At the same time, he was moving into Sunni turf and infringing on tribal prerogatives. This had the effect of alienating his would-be allies.

But the balance has shifted. ISIL has more strength than al Qaeda in Iraq ever did and its enemies on the ground are weaker. Without war, ISIL is a fringe terrorist organization. With war, it is a state.

So long as it exists, the Islamic State’s borders will always be bloody.

This is where I am supposed to advocate a brilliant strategy to defeat ISIL by Christmas at some surprisingly reasonable cost. But it won’t happen. The cost to defeat ISIL would be very high and would require a multi-year commitment. I wish, very much, that the United States had taken ISIL and its predecessors more seriously after the Surge in 2007—but we did not, and that represents both a political and analytical failure. In a post-Benghazi world, looking toward the 2016 Presidential election, the political consensus to incur the risks and costs of destroying ISIL is tremendously unlikely. And even then, success hinges on dramatic political shifts in both Iraq and Syria that under the best of circumstances will require years. (Despite a new Iraqi Prime Minister, there is no short-term prospect for credible governance across either Iraq or Syria.)

It would be irresponsible to support a national security policy dependent on infeasible military operations or ludicrous assumptions about an enemy’s shortcomings. War is a matter of matching ends, ways, and means – including political and popular support. It would therefore be irresponsible to support a policy that would require a level of commitment that our political institutions do not possess. Our discourse is too broken. Short of a major terrorist attack, our leaders do not have the ability to produce consensus. And without real national consensus to sustain a strategy, there is no viable mechanism to defeat ISIL.

Advocating the defeat of ISIL over the short-term without acknowledging what will be necessary to achieve that end is a recipe for mission creep. Mission creep is a recipe for policy failure because the American people will not allow sustained investment in a policy they did not commit to originally.

This is the most important strategic lesson from Iraq: Don’t bullshit the American people into a war with shifting objectives (even if those goals are important) because they will not put up with that commitment long enough for those goals to be achieved. This is not a call for pacifism; it is a call for fighting to win, which requires sustained commitment, which requires forthrightness in our discourse about whether to choose war. We should only fight if we are fighting to win, and we will only win when we commit as a country—not 51 percent, or the viewers of one cable news station or another, or because one party or faction has managed to back a president into a political corner. The country must be ready to accept the sacrifices necessary to achieve grand political ends. Until then, any call to “defeat ISIL” that is not forthright about what that will require is actually an argument for expensive failure.

Brian Fishman is a War on the Rocks Contributor and a Fellow at the New America Foundation.