Well into the Syrian civil war the Assad regime has made a costly miscalculation by staging a significant chemical weapons attack. The U.S. and its allies have been wary of a full-scale military operation in Syria, but spurred by this attack they are now preparing to intervene. To succeed western allies must be focused not only on degrading Syrian capabilities but also on avoiding mistakes beyond the short term that they made in Libya and Iraq.

The U.S. needs to intervene with as much legitimacy as it can muster, which appears to have a fighting chance in Congress (though Congressional leaders would be unwise to hold any votes ahead of the impending report from UN weapons inspectors). But the Bush Administration’s legacy continues to take a toll when it comes to the credibility of the U.S., not only at home but around the world. David Cameron seriously miscalculated in this respect already, although odds are the House of Commons will back British involvement in a second attempt at authorization once the UN issues what is likely to be a game changing report. Despite Russia’s prevention of authorization from the UN Security Council, the growing certainty about Syria’s multi WMD use is sufficient justification in the eyes of numerous American allies starting with the French (a list that will grow with the declassification of additional evidence and the weight of the UN’s moral authority, if not in a UNSC resolution at least in a clarifying report).

The western operation, however, needs to go beyond a mere “shot across the bow.” To reestablish a deterrent effect for rogue regimes like Assad’s, the operation will need to be more decisive. Yet it is even more important for the West to degrade Syrian military capabilities enough to turn the tide in the war. Doing less would allow Assad to appear to be standing up to the West yet again. And whatever deterrent effect were regained, it would slowly fade as the civil war grinds on indecisively. Moreover the war has already spilled over the Turkish, Jordanian, and Lebanese borders, and is rapidly on its way to becoming a sectarian regional war that would harm the security interests of a long list of countries including the U.S.

Notwithstanding some high placed naysaying U.S. and western credibility are in fact at stake, not only in Tehran and Pyongyang but also in the redoubts of al-Qaeda’s increasingly active affiliates and Hezbollah–not to mention Moscow and Beijing. Most of all, the U.S.-led intervention as currently designed would be a missed opportunity to tilt events on the ground toward what is already a stated western aim: the removal of the Assad regime. The mass bloodshed and destabilization of a critical region need to be stopped, and the authority of the international community restored.

As Steven Cook points out, as designed the intervention would take a greater toll on the Syrian people than a serious deter and degrade operation. Nora Bensahal convincingly assesses the need for more serious strategy. Charles Krauthammer points out the same in somewhat more robust terms. Gideon Rachman underlines the major joint interests at stake and the indispensable need for U.S. leadership. Richard Betts overestimates the importance of carrying public opinion and congressional support compared to the collective weight of interests, threats, and principles. And the controversial ICG Report questions all of this with an odd assessment that no outside intervention can change realities on the ground. Moreover my Duck colleagues are all over this, particularly in two sharply clarifying pieces by Charli Carpenter and Staci Goddard.

It is possible the Administration’s current plan of operations will succeed, leaving a stalemate on the ground in the Syrian civil war but a regime that will no longer resort to the use of sarin gas to terrorize citizens it believes sympathize with its opponents. But it is highly likely there will be retaliation from Hezbollah and possibly Iran as well, aimed at the West, Israel, or both; Syria itself might use short range Scud missiles to attack Jordan or Turkey, or fearing it has little to lose actually use sarin on its own people again. Before long, à la Libya the U.S. and its allies would likely find themselves in a full-fledged regime change operation anyhow.

Western and Gulf allies need to carry out a joint military operation that will seriously degrade Syrian capabilities to the point that opposition forces can remove the Assad regime from power without requiring an invasion from western ground troops. Critically, they should also now begin planning their “day after” strategy for Syria, ironically a point that seems almost entirely lost in the current debates about the wisdom of this intervention.

The military phase of the operation needs to involve a sufficient number of sorties by allied fighter bombers and cruise missile attacks to destroy the Syrian air-defense system, its Scud missiles, the critical portion of its air force (including the helicopters provided by Russia), the runways Russia and Iran use to supply Syria, the artillery used to stage chemical weapons attacks, and several key bases and command and control centers. The sorties should be flown by U.S.-based B-2 bombers, B-1 bombers from Qatar, and French, British, and Turkish aircraft flying out of the NATO Incirlik air base nearby in Turkey. If American and British submarines join the four American Arleigh Burke destroyers there will be ample tomahawk capacity for sustaining an air operation well beyond what was carried out in NATO’s Libyan operation.

After achieving this collective initial military objective the Gulf allies should set up safe zones in the north and south of Syria as the Western allies install a no-fly zone, which will allow the opposition forces to achieve their objective on the ground within weeks instead of months. But only if the Western allies also at long last join with the Gulf allies to augment the arming of the Free Syrian Army with the anti-tank and anti-aircraft weaponry it has long sought from the West. It is in fact possible to achieve this without weapons ending up in the hands of the pro al-Qaeda jihadist opposition forces, as the latter are largely fighting in the north and east while the 30,000 strong FSA is fighting in the Damascus vicinity. In fact, FSA commanders are convinced they can oust the regime were western allies merely to attack a handful of Syrian bases and artillery batteries near the capital.

What the FSA is not capable of handling on its own is the aftermath of its probable military victory. The most important lesson learned from the intervention in Libya was the need to have a strategy in place for “the day after,” i.e. the phase that begins once the regime falls. In the absence of a post conflict phase of that NATO operation, militias were allowed to transfer enough Libyan weaponry to Mali that it sparked a successful rebellion there that ended up requiring an additional western operation (at present both the EU and NATO are in the process of doing what they should have begun doing the day Tripoli fell, for the stabilization task in Libya is now more uphill by several orders of magnitude).

The U.S. and its allies should therefore plan for not only a military phase of the operation, but also a post-conflict phase in order to stabilize post-Assad Syria. Without this critical conclusion to the intervention, Syria will likely slide back into conflict in which case events would more than likely still lead to a wider regional war.

Stabilizing post-Assad Syria will not be easy to accomplish. More than a decade of stability operations in Iraq and Afghanistan have yielded uneven results, and few would welcome a prolonged effort to achieve stability in yet another Middle Eastern country. But the consequences of no “day after” operation in Syria would be even more substantial than they were in Libya. The subsequent struggle for power between Sunni moderates and the al-Nusra Front could drive the future of the Middle East. And quite simply a radical al-Qaeda affiliate governing next door to Israel, Jordan, and Turkey would be intolerable.

A primary lesson from the West’s experience in Iraq and Afghanistan is that time wasted in establishing post-combat stabilization yields mistakes that take years to overcome. Organizing a credible multilateral post-conflict stability effort in Syria will be arduous, so governments need to begin planning it now.

Several short term missions would require immediate attention. Chemical weapons will need to be placed under international control and then destroyed. Refugees will need to be repatriated. Minority Alawites will need protection from revenge attacks; the Kurds in the northeast will need the same. And critically, radical Islamist forces will need to be disarmed. This is the key to dealing with the greatest fear intervention opponents have about pursuing indirect regime change.

In the medium term the new government’s security and police forces will need to be trained. Rule of law programs for the courts will need to be put into place. Eventual elections will need to be planned. And Syria’s destroyed infrastructure will need to be rebuilt. Successful completion of these tasks, with the burden shared widely among western and regional allies, will keep al-Nusra and the forces of radical Islam at bay in Syria (especially if they are locally led and only foreign assisted). All of this will thwart Iranian and Hezbollah influence in the region which recently has been steadily increasing, an effect that is profoundly in the joint security interests of the allies and Israel in particular.

There will also need to be a limited military component to the post conflict phase. The U.S. will need to play a role, but it cannot bear a major burden in Syria like it did in Afghanistan. Along with Europe it would need to provide a modest force for security and training, but individual nations like Turkey need to take the lead military role. Moreover, wealthy Gulf states will need to open their purses much more than before.

The civilian operation should be Western with the EU in the lead. Though the U.S. has seriously degraded its Civilian Response Corps, it should offer as many civilian experts as it can spare. The State Department experts who are currently training the Syrian opposition in non-violent resistance in Turkey should remain and join a larger EU civilian post-conflict operation in Syria.

And let us not forget the vital importance of diplomacy. In-between Congressional and Parliamentary authorization and the initiation of the military phase of the operation, western diplomats should vigorously work the Geneva process to see what might be gained at the negotiating table (with Syria, Russia, and even Iran). As odds are against any noteworthy breakthrough ahead of the intervention, diplomatic efforts should continue during the military phase and on through the post-conflict stabilization phase as western leverage will increase in proportion to the degrading of Syria’s capabilities and the harm meted out to its supporters’ interests.

Ironically, there is a fair chance that Russia will back authorization for the post-conflict phase at the UN once it is clear Assad will go. At present Putin and Lavrov have made sticking it to the U.S. a higher priority than serving Russia’s own shared interest with the West in stabilizing the Middle East and avoiding a regional war (almost entirely for domestic political reasons, in fact). At the point that it becomes clear Assad will not lead Syria for much longer, a diplomatic window of opportunity will open with the Russians. If the U.S. were proactive about making it clear to Russia that it can be part of the stabilization effort, incentives for its cooperation will increase significantly. Russian peacekeepers would become a real possibility.

Even more ironically, the Iranian leadership is quietly looking for a way around the Syrian obstacle to improved relations with the U.S., hence its own condemnation of Assad’s use of chemical weapons (not so much the fact that it was the victim of such during its war with Iraq). Since Europe joined the American-led sanctions against it, the toll has been high inside the country. This is why Ayatollah Khamenei engineered the victory of Iran’s new somewhat moderate President, Hassan Rouhani. Finally, Hezbollah would experience a significant enough setback that dynamics in Lebanon might actually improve over the next several years.

Without a decisive U.S.-led intervention it is difficult to predict which way the current conflict in Syria will go, but if opposition forces with an assist from the West were ultimately successful in defeating the Syrian army then there is little doubt the onus would be on the West to ensure post-Assad stability in this pivotal Middle Eastern country.