FOR all his undertakings to present a cogent case for Britain to jump on the US-led bombing spree over Syria, David Cameron has done no such thing.

His appeal to the House of Commons amounted to little more than a jumble of half-truths and wishful thinking to advance the idea that a minimal increase in bombing random targets by British planes, added to that of France and the US, could “degrade” Isis and the reduce its threat to Britain.

Once again the Prime Minister declared that Isis has its headquarters in the Syrian city of Raqqa where “some of

the main threats against this country are planned and orchestrated.”

He adduced no evidence to prove this assertion any more than he did to justify his claim that British involvement would make a military difference.

Cameron made no effort to answer key questions posed last week by the Commons foreign affairs select committee for the simple reason that he has no credible response to them.

The mere fact that committee chairman Crispin Blunt has swung in behind his party leader despite having received no credible reply to the doubts he personally raised a few days ago does not strengthen Cameron’s case.

His vague reference to “moderate” forces — 70,000 would you believe? — being supported to take and hold land to “relieve suffering,” as seen in Kobane, ignores the reality that the only systematic military resistance to Isis is by the Syrian army and Kurdish YPG units who are loth to fight outside Kurdish areas.

As bravely as Kurdish units fought in Kobane, others retreated initially from Sinjar in Iraq in the face of an Isis advance, leaving the mainly Yazidi population to face slaughter, rape and enslavement.

Sinjar’s subsequent liberation by Kurdish and Yazidi peshmerga forces has revealed a network of subterranean communication tunnels and bomb shelters.

Is it beyond Cameron’s imagination to believe that these exist also in Raqqa which has been in Isis hands since March 2013?

Those least likely in Raqqa to have deep bomb shelters are the half-million-strong civilian population who, if the PM gets his way, will be slaughtered by bombs and rockets while Isis fighters remain below ground confident that no infantry forces will follow up the aerial bombardment.

Labour leader Jeremy Corbyn and the Scottish National Party’s Westminster leader Angus Robertson were correct to draw attention to the gaps in Cameron’s case and to reiterate the unanswered questions.

Despite the government and media onslaught, there remains little appetite among Labour, SNP, Plaid Cymru, Green and Liberal Democrat MPs for another bombing extravaganza.

Their doubts can only increase as awareness grows of the failings of so-called “precision bombing,” such as in this week’s obliteration by French aircraft of a Mosul school in which 28 children perished.

New Labour zealot Chris Leslie increasingly resembles one of those Japanese soldiers emerging from a Pacific island jungle in the 1960s and discovering to his horror that the war is over.

He affects to believe that the UN security council resolution urging member states to take “all necessary measures” to prevent Isis terrorism in Syria and Iraq offers carte blanche for more bombing.

Resolution 2249 did not provide a legal basis for military action and does not invoke Chapter VII of the UN charter that authorises the use of force.

Bombing campaigns have to work in tandem with ground forces, as in Russian air force co-operation with the Syrian army. Otherwise, they are futile gestures that also pose a deadly threat to civilians.

If Cameron and his armchair generals want to seriously affect Isis, they should start by questioning the military and financial assistance given to terrorists in Iraq and Syria by Turkey, Saudi Arabia, Qatar and other Gulf dictatorships.