U.S. strike would aim to punish Assad, not turn tide of war

U.S. and European officials say a short, sharp attack - perhaps entirely with cruise missiles - is the preferred response to what they believe is Assad's responsibility for a chemical weapons attack on rebel-held areas last week. If such a strike goes ahead, President Barack Obama's administration will have to select its targets with extreme care as it tries to deter not only Assad but also Syria's ally Iran over its nuclear programme. "The administration has to decide what its objective is - punishment to show that there is a price and to re-establish a deterrent, or to change the balance of power in Syria," said Dennis Ross, a top White House adviser on the Middle East until late 2011. "I suspect it will be geared towards the former." NATO air strikes in 2011 helped to change the course of the Libyan civil war, allowing rebels to overthrow Muammar Gaddafi, but Obama is unlikely to opt for something similar in Syria. U.S. officials said the Pentagon has submitted a range of possible attack plans for Syria to the White House, and analysts believe the scope would be modest.

"I think it will happen but it will be minimal, just enough to show the world that we did something," said Hayat Alvi, lecturer in Middle Eastern studies at the U.S. Naval War College. "The broader goal is not to get the U.S. involved too deeply - and especially not to allow any boots on the ground."

Defense Secretary Chuck Hagel said the U.S. military is ready to act immediately should Obama order action.

The United States and its allies were strengthening their forces in the region even before hundreds of people were killed in rebel-held suburbs of Damascus last Wednesday. Syria has blamed the rebels but Washington, London and Paris say they have little doubt it was a chemical strike by Assad's forces.

Without some action soon, officials worry that Assad will feel he can resort to chemical weapons again with impunity - a year after Obama declared their use a "red line" that, if crossed, would require strong action.

Some also fear inaction in Syria could cast doubt over other U.S. "red lines", encouraging Iran to pursue a nuclear programme which Tehran says is peaceful but the United States and its allies including Israel believe aims to produce weapons.

Any failure to strike Syria could also prompt Israel to take matters into its own hands by attacking Iranian nuclear facilities, causing yet more upheaval in an already highly unstable region.