Israeli jets reportedly destroyed a shipment of missiles at Damascus International Airport on Friday and carried out more airstrikes on the outskirts of the Syrian capital Sunday morning. The attacks over the weekend further complicated the task of U.S. and international leaders looking for a resolution to the country’s two-year-old civil war, especially after President Bashar al-Assad’s government threatened retaliation against Israel. The Obama administration, already planning to increase its involvement in Syria, may take action quickly, reports Karen DeYoung:

Senior officials said the deployment of U.S. troops to Syria remains unlikely, but they have indicated that a decision will come within weeks on options ranging from the supply of weapons to the Syrian rebels to the use of U.S. aircraft and missiles to ground President Bashar al-Assad’s air power by destroying planes, runways and missile sites inside Syria. . .

The apparent Israeli strikes — following reports in recent weeks that Assad’s forces probably deployed chemical weapons in unknown quantities — appeared to bolster the case of those who have long favored direct U.S. support for the rebels.

Determining whether chemical weapons were used and by whom has proven difficult for observers of the conflict. After a U.N. official told a Swiss broadcaster that there was evidence the rebels, not the government, may have deployed the weapons, U.S. officials disagreed:

“We are highly skeptical of suggestions that the opposition could have or did use chemical weapons,” White House press secretary Jay Carney told reporters. “We find it highly likely that any chemical weapon use that has taken place in Syria was done by the Assad regime. And that remains our position.”

Interactive Grid: Keeping track of the conflict in Syria through videos, images and tweets.

A U.S. official, speaking on condition of anonymity to discuss the matter candidly, said: “We’re trying to get as many facts as possible to understand when and how such things were used. But our understanding has been that the armed opposition does not have such weapons . . . that they do not have such things in their arsenal.”

At WorldViews, Max Fisher wonders if the weapon used might have been improvised using chlorine purchased commercially:

A March Reuters story described a possible chemical attack in the northern town of Khan al-Assal, near Aleppo, after which residents said they could smell chlorine. The Telegraph reported at the time that Syrian regime forces accused rebels of using a homemade chlorine solution in the attack. . .

Syria analyst Michael Weiss, also writing at the time, noticed that both Syrian state media and opposition groups independently reported the attack and blamed the other side. That’s not something either side would seem likely to do if they had actually conducted the attack, particularly given the sensitivity around chemical weapons. Both appeared, in other words, equally surprised. . .

Taken together, all of this information makes it difficult to say with much certainty whether or not chemicals are being deliberately deployed in Syria (in a country with such large stockpiles, accidental exposure is a possibility), much less by whom. (Read the rest here.)

President Obama has suggested that his administration would adopt a more aggressive approach in dealing with the situation in Syria if Assad’s forces began using chemical weapons. Post opinion writer Jennifer Rubin criticized the administration’s inaction despite the recent reports that such weapons might have been used:

When a U.S. president is this passive and unwilling to act in accord with its words, the West and the Sunni states can take comfort in knowing that Israel is there to rein in the mullahs and their surrogates. . .

The United States is obviously unwilling to back up its rhetoric with action. Syria is a dress rehearsal  for the bigger conflict between Iran and the West. There, too, one suspects, Israel will be forced to act. For what Israeli prime minister could rely on this administration to act? If Obama won’t take on Syria, there is little chance he’ll make good on his threats to Iran.