London: Any strike by the United States and its allies on Syria will probably aim to teach President Bashar Al Assad — and Iran — a lesson on the risks of defying the West, but not try to turn the tide of the civil war.

US and European officials say a short, sharp attack — perhaps entirely with cruise missiles — is the preferred response to what they believe is Al 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 Al 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.

US 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 US Naval War College. “The broader goal is not to get the US involved too deeply — and especially not to allow any boots on the ground.” Defence Secretary Chuck Hagel said the US 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 Al Assad’s forces.

Without some action soon, officials worry that Al 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 US “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.

Least worst option

Most officials who talked to Reuters said the possibility of allied and civilian casualties was a top consideration.

“It’s about the least worst option,” said a European defence source on condition of anonymity. “No one wants the risk of pilots being captured or killed.” Manned aircraft could still be ultimately used — Israeli jets have already raided Syrian targets on several occasions, proving it is possible.

US F-16 jets have remained in Jordan after an exercise earlier this year. The US air force could also reinforce its Turkish airbase at Incirlik while B2 long-range bombers could fly from the continental United States, unseen by Syrian radar.

Gulf and other regional allies might provide useful intelligence, Western officials said, although their direct involvement in initial strikes was seen unlikely. The main focus would be protecting them from any retaliation by Damascus.

Syria’s conventional forces still pack considerable punch, experts say, including anti-ship missiles that could hit vessels nearby in the Mediterranean and conventional rockets that could hit neighbouring countries including Israel.

Last year, Assad promised not to use chemical weapons within Syria’s borders — but explicitly threatened foreign countries if they attempted to impose outside “regime change”. Western officials believe Syria retains considerable stocks including VX gas, regarded as much more lethal than the sarin suspected to have been used in last week’s attack near Damascus.

Such worries were a major factor in Turkey and Jordan requesting US and Nato Patriot missile batteries now based along the border to shoot down enemy missiles.