It is now beyond all reasonable doubt that nerve gas(es) were used as a weapon in the civil war in Syria. But the key question that remains is “Which group was the instigator?” Here’s a short list of the likely suspects:  The Assad regime, the anti-Assad group that is UNaffiliated with Al Qaeda, and the Al Qaeda-linked anti-Assad antagonists.

Each of these groups has its own separate motive for introducing a WMD into the battlefield. Assad would like to inflict heavy casualties on his opposition. The group disconnected from Al Qaeda could use the gas, blame it on Assad and then use that as a pretext to beg for US intervention. The Al Qaeda-types would have the dual motive of creating havoc AND drawing the US into full-fledged involvement much as they did with the 9-11 attacks which, as we know, provoked the war in Iraq.

The president and our intelligence community, in concert with UN inspectors, have the unenviable job of sorting all this out. It then becomes Obama’s job of plotting a course of action that is not only proportional, but avoids our getting drawn into the middle of a civil war that would be costly in the extreme in blood and treasure, and be rife with the potential for unmanageable unintended consequences.

If the Assad regime is to be the target of a proportional response, it must be small enough in scope so that Syria is not further destabilized. Al Qaeda would like nothing more since its goal is complete disruption of the country’s government followed by the installation of a strict Islamic fundamentalist one. That outcome would pose an immediate threat to us, but especially to Israel. The president has signaled an awareness of all this by making it clear that he is not at all interested in regime change.

The foregoing should provide a basic sense of just how complex the situation in Syria is. Obama’s mastering it with the right response aimed at the appropriate target comes close to winning at a three-level chess game. He should not be forced to go it alone absent the advice and consent of our Congress. The president is asking for that and today’s news brings word that both House Speaker Boehner and Majority Leader Cantor are in his corner. Support from the Senate leadership should also be forthcoming.

Whatever course Obama takes and whatever the outcome, it is a welcome sight to see ranking members of Congress rallying behind him. Any time our nation becomes actively engaged as a direct participant in hostilities the decision to do so should be a shared decision so that eventual credit or blame is also shared. Too often in the past, Congress has shirked its Constitutional responsibility by passing open-ended war-making resolutions and then giving the president alone, free rein to do as he pleased. In our recent history, there is no better example of this than the war in Iraq, the negative effects of which remain with us to this day.