Supporters of the president’s proposal contend that a limited punitive strike can be carried out without inflaming an already volatile situation. But a number of diplomats and other experts say it fails to adequately plan for a range of unintended consequences, from a surge in anti-Americanism that could bolster Syria’s president, Bashar al-Assad, to a wider regional conflict that could drag in other countries, including Israel and Turkey.
“Our biggest problem is ignorance; we’re pretty ignorant about Syria,” said Ryan C. Crocker, a former ambassador to Syria and Lebanon, who has served in Iraq and Afghanistan and is dean of the Bush School of Government and Public Service, Texas A&M University.
The American strike could hit President Assad’s military without fundamentally changing the dynamic in a stalemated civil war that has already left more than 100,000 people dead. At the same time, few expect that a barrage of cruise missiles would prompt either side to work in earnest for a political settlement. Given that, the skeptics say it may not be worth the risks.
“I don’t see any advantage,” said a Western official who closely observes Syria.
In outlining its tentative plans, the Obama administration has left many questions unanswered. Diplomats familiar with Mr. Assad say there is no way to know how he would respond, and they question what the United States would do if he chose to order a chemical strike or other major retaliation against civilians.
That would leave the United States to choose between a loss of credibility and a more expansive — and unpopular — conflict, they said. “So he continues on in defiance — maybe he even launches another chemical attack to put a stick in our eye — and then what?” Mr. Crocker said. “Because once you start down this road, it’s pretty hard to get off it and maintain political credibility.”
For the United States, the challenge is to deliver the intended message to Mr. Assad without opening the door to a takeover by rebels linked to Al Qaeda, the collapse of state institutions, or a major escalation by Syria’s allies. Skeptics doubt that the United States — or anyone else — has the information to calibrate the attack that precisely.
That is partly because the United States is preparing to inject itself into a conflict that is no longer just about Syria, but has become a volatile regional morass that pits Iran and Hezbollah, the Shiite militant group in Lebanon, against Qaeda affiliates backed by Saudi Arabia and other Persian Gulf benefactors.
Iran’s and Syria’s defense ministers threatened on Friday to unleash attacks on Israel if Mr. Assad was in danger. While Hezbollah has said it would wait to see the scale and nature of the attacks before responding, in practice, analysts close to the organization said, it is probably prepared for any contingency.
There is also concern that Shiite-led Iraq could send thousands more militants to help Mr. Assad if it believed he was truly threatened, and that such a step would in turn further rally and embolden Sunni jihadists on both sides of its border with Syria.
Many diplomats and analysts consider retaliation unlikely, but the consequences could be grim. Israel has vowed that if Hezbollah attacks it again, it will respond forcefully, drawing Lebanon into war. And if Syria lobbed missiles into Israel and it responded with airstrikes through Lebanese airspace that threatened Mr. Assad further, Hezbollah would consider that further justification to attack Israel.
Even without such a direct entanglement, Lebanon could be very vulnerable. It has recently suffered its worst sectarian violence in years: a car bomb in Shiite Hezbollah territory in the Beirut suburbs, and two at Sunni mosques in the northern city of Tripoli. Lebanese authorities accused Syria on Friday of involvement in the Tripoli attacks, and intelligence officials fear such bombings could increase.