President Obama stepped off his plane in Israel this week amid a new flurry of reports suggesting that chemical weapons may have been used in Syria.

The Syrian government charged that rebel forces used the illegal weapons in an attack that killed 25 people and wounded 86 in the village of Khan al-Assal near the northern city of Aleppo, which has long been wracked by intense fighting.

Syrian opposition leaders denied responsibility for the alleged attack and blamed the government, pointing out that they do not even have chemical weapons or the kind of large rocket that was apparently involved in the attack. The rebels claim that the Assad regime launched this crude propaganda effort to discredit the rebels, with whom it has been locked in a two-year-long war that has claimed more than 70,000 lives.

White House spokesman Jay Carney said that there was no evidence that the rebels had used chemical weapons and warned Assad not to use the allegations as a pretext to launch a chemical attack. White House chief of staff Denis McDonough told CNN on Tuesday night that if it turned out that the regime had used chemical weapons, “this is a game-changer and we will act accordingly.”

In December, President Obama warned the Assad regime against using chemical weapons: “The use of chemical weapons is and would be totally unacceptable. If you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable.”

Heritage Foundation defense expert Steven Bucci has stressed the need for U.S. contingency planning to contain the threat posed by Syrian chemical weapons, particularly to prevent them from falling into the hands of terrorists if the regime implodes.

It will take time to investigate the allegations and find evidence of a chemical attack. And one incidental use of chemical weapons, even if proven, would not automatically trigger a direct U.S. military response. But the persistent reports of chemical weapons attacks and the intensifying fighting underscores the growing dangers posed by the Obama Administration’s “lead from behind” policy on Syria.

On the first day of his Middle East trip, President Obama has received an urgent wake-up call: He needs to quickly develop a more effective policy for containing the destabilizing spillover effects of Syria’s civil war.

See “Obama’s Middle East Trip: Security Goals Should Be the Highest Priority.”