Why Cameron's case for Syria airstrikes is highly contentious

David Cameron’s case for UK military action in Syria has several highly contentious key points.

“There is a credible military strategy to defeat Isil in Syria as well as Iraq”

If there is, no one has told the US. 

In private briefings and in public testimony to Congress, a long line of senior American officers have acknowledged frustration with the battle against Islamic State. General John Allen, who was in overall charge of the US campaign in Syria and Iraq, has quit after a year.

A marine commander, Lieutenant General Robert Neller, offering his best assessment of how the war is going, described it as a “a stalemate”.The US-led coalition engaged in air attacks in Syria and Iraq had by the middle of last month conducted 7,600 attacks (4,900 in Iraq and 2,700 in Syria). Their main problem is finding targets to hit. Isis has long learned the danger of deploying in mass in the open.

The pilots frequently return to base without firing missiles or dropping bombs, partly they say because of fear of hitting civilians but mainly because after a year there is little left to hit. So what can the UK add? Nothing much that is not already being done by the US, France and other allies.

The bombing raids do serve a useful purpose in that Isis fighters cannot move around as easily as they once did. It makes them more cautious, having to watch the sky for a drone or fighter aircraft.

“Airstrikes can degrade Isil and arrest its advance”

It is debatable whether Cameron’s claim in his response to the foreign affaris committees is true. The coalition repeatedly says it has shrunk the geographical area controlled by Isis by 30% in the past year, but in that same period Isis has advanced on and taken Ramadi in Iraq and Palmyra in Syria.

In any event, Cameron goes on to concede that air strikes alone cannot defeat Isil.Who is going to provide these troops on the ground? The Obama administration is opposed, other than deploying more ground troops. British military chiefs laugh off suggestions of committing tens of thousands of UK troops to take Raqqa.

So who is going to do it? The Kurds are too small a force, with little interest in fighting beyond neighbouring territory. The Iraqi army is riven by religious and ethnic divisions. The Free Syrian Army and similar groups have so far been largely ineffective – although Cameron says there are 70,000 anti-Assad non-Isis fighters available for the task.

There are so many questions to be answered. Does this mean the Syrian president Bashar al-Assad will be left in place? What other military options are there? More special forces targeting the Isis leadership or helping to pinpoint targets for air raids? Begin to destroy oil fields, the main source of Isis finance?

The main reason for attacking Syria appears to be a show of solidarity with the US and France.