Sen. John McCain, when asked about President Barack Obama's plan to punish the Syrian regime for alleged use of chemical weapons against its citizens, rightly emphasized that any action should have "lasting impact." Yet Assad's back is to the wall; he may feel there is nothing to lose by fighting with any and all resources at his disposal, even weapons of mass destruction. Syria is not a signatory to the Chemical Weapons Convention of 1997, and Assad's targets for chemical WMD deployment seem to be growing in number and deadliness.

While horrifying, Assad's use of chemical weapons against the Syrian population on multiple occasions over the past two years is in line with his practice of killing citizens who aid or abet opponents. The Syrian military's preferred tactic has been to bomb towns and neighborhoods with conventional weapons and occasionally WMD, then go in with tanks and infantry to root out remaining opposition. Unleashing chemical weapons upon residents of northwest Damascus on August 21 followed this pattern. When the military and its shabbiha auxillaries are pushed back to their bases, they switch tactics -- lobbing munitions into the midst not only of rebel forces as diverse as the Free Syrian Army and al-Qaeda-affiliates, but also of nearby civilians. Those bases are usually resupplied by helicopter, unless there are runways to land fixed-wing aircraft.

So, when it comes to punishing Assad, choosing sites whose obliteration will most seriously degrade the Syrian regime's ability to further prolong civil war could save thousands of innocent lives. Removing key military capabilities also may forestall American and European boots on the ground amidst factions that mistrust each other politically, ethnically and religiously.

Destroying Syria's chemical weapons would appear to be the most effective and conflagration-neutral action. It would put all factions on a more equal footing, plus have the lasting impact of removing those WMD from use against combatants and civilians alike. The tactical dilemmas, however, are insufficient knowledge of locations like al-Rastan, Hama, Aleppo, Palmyra (Tadmur), Damascus and al-Muharram, and of storage conditions to ensure total destruction of chemical precursors and assembled warheads. After all, it is essential to prevent some from being salvaged and reused by Assad's troops or by his opponents, including Islamist fighters who abhor the West. Moreover, less-than-precise strikes against chemical WMD facilities could release toxins into the air, soil and water -- harming the very people U.S. actions seek to protect.

In the absence of completely eliminating Assad's chemical WMD capability, what sites could the U.S. and its partners remove to ensure lasting impact?

One set of possible targets are key command and control locations such as the hills around Damascus on which the presidential palace, the Assad family palace and Fourth Brigade's headquarters -- all connected by tunnels -- are located. Taking out those installations and the communications grid linked to them would greatly reduce the ability of Assad and his inner circle of commanders to direct forces still loyal to them across Syria. Yet, given the deeply-recessed construction of the regime's nerve-center, those locations between Qatana to al-Ruhhaybah would have to be pulverized by bunker-busting aerial bombardments.