A sense of unreality and lack of seriousness flavours the British Government’s approach to bombing Isis in Syria in retaliation for the murder of British citizens in Tunisia. Give due allowance for the British tradition of procrastination and there is still something strangely languid about our lead-up to the moment when we try to kill members of the most dangerous organisation in the world.

The delay to adding Syria to Iraq as a target for RAF airstrikes is being explained as a laudable attempt to win cross-party agreement on the decision to bomb. In practice, it reflects the contradictory nature of British – and American – policy towards the war in Syria. Of course, the Government tries to give the impression of seamless continuity between its wish to bomb Syria in 2015, in the wake of the Sousse massacre, and a supposedly similar intention in 2013, after the use of poison gas in Damascus, which was rejected by the House of Commons. The one little detail not mentioned in this self-serving narrative is that, on the first occasion, we were intending to attack the Syrian army and, on the second, some two years later if it goes ahead, we will be attacking Isis, the Syrian army’s main opponent.

The changed identity of our enemy did not come across in a Downing Street briefing to correspondents last week. The briefer said: “The PM has long thought that Isil [Isis] poses a threat to Britain and Isil needs to be destroyed in Syria as well as in Iraq. That’s exactly what he said in the debate in the Commons last September. He set out in the debate that there was a strong case for the UK to do more in Syria and that remains his view. But he also said he wanted consensus in the House.”

Well, that should rattle those bad men in Raqqa. It is unlikely that they pay attention to House of Commons debates, but if they do, then the one last week about intervention in Syria sounded a feeble but probably realistic note. The sad truth is that in the fourth year of the Syrian war, Britain is still muddled over which side it is on.

It is estimated more than half of Syria is now under Isis control (Getty) (Getty Images)

Crispin Blunt, chairman of the Commons Foreign Affairs Select Committee, said he wanted to know whether any intervention would be a “battle-winning decision”. This is not going to happen since, despite some 5,000 US airstrikes in Iraq and Syria, Isis has recently won military victories in both countries. Containment of Isis using airpower has failed. Mr Blunt found it “frustrating” that the debate around military action in Syria “is not going to make any difference to the outcome”. It is true that the US-led airstrikes have not proved the “game changer’ on the battlefield they were supposed to be.

Many MPs saw the nature of the dilemma very clearly. Julian Lewis, the newly elected chairman of the Commons Defence Committee, said that in the past “the Government wanted to remove Assad without helping al-Qaeda or similar groups that subsequently became Daesh [the Arabic acronym for Isis]. Now we apparently want to remove Daesh, but without helping Assad. These two things are incompatible. It is a choice of evils”.

This is largely true. The Syrian Observatory for Human Rights estimates that more than half the area of Syria is now under the control of Isis. President Bashar al-Assad probably holds another third, though these proportions are a little deceptive because the government still holds most of Damascus, the main cities and the roads linking them. But the Syrian army has been losing ground since March this year and an expanding area is being seized by a coalition led by Jabhat al-Nusra, the al-Qaeda affiliate, in the north, which is reportedly supported by Sunni states such as Turkey, Saudi Arabia and the Gulf monarchies.

There is an attempt to rebrand al-Nusra as kinder, gentler jihadis, but those who believe this propaganda should reflect on al-Nusra’s unstinting praise for the perpetrators of 9/11. Assad may be about to lose the city of Daraa in the south to the Southern Front, an alliance of groups which present themselves as more moderate than Isis or al-Qaeda, and is financed and supported by the Military Operations Centre (MOC) in Amman that is staffed by agents from the US, Jordan, Saudi Arabia, UAE and other anti-Assad countries.

Of course, many states down the centuries have supported multiple sides in somebody else’s civil war. A problem is that in Syria this may no longer be sustainable because it is Isis and the most extreme Islamist groups that will ultimately benefit from the weakening of Assad and the government in Damascus. In the case of the Southern Front, often advertised as an anti-Assad force which is not extreme jihadi, its guise may be adopted to hoodwink foreign backers. The Syrian expert Aron Lund writing in the online magazine Syria in Crisis says that the “adoption of MOC-provided talking points” by members of this alliance are likely “to be more opportunistic than heartfelt”.

Ancient monuments under Isis threat Show all 8 1 /8 Ancient monuments under Isis threat Ancient monuments under Isis threat Isis seizes Palmyra The ancient oasis city of Palmyra Getty Ancient monuments under Isis threat Isis seizes Palmyra A partial view of the ancient ruins Getty Ancient monuments under Isis threat Isis seizes Palmyra The ancient Palmyra theater Reuters Ancient monuments under Isis threat Isis seizes Palmyra A view of the ancient Syrian city of Palmyra Getty Ancient monuments under Isis threat Isis seizes Palmyra The Temple of Bel Reuters Ancient monuments under Isis threat Isis seizes Palmyra Palmyra's famous graves AP Ancient monuments under Isis threat Isis seizes Palmyra The ancient castle Getty Ancient monuments under Isis threat Isis seizes Palmyra A sculpture depicting a rich family from the ancient Syrian oasis city of Palmyra, displayed at the city's museum Getty

Assad’s forces are exhausted but are not close to collapse, though his hopes of retaking the whole of Aleppo and advancing into other rebel-held parts of Syria are gone; he is vulnerable to a push from the Isis-held half of Syria to the east. At some point, the US and UK may end up bombing Isis when it is fighting an increasingly battered Syrian army. This will get more difficult as time goes on and Isis expands into Damascus, Aleppo, Homs and Hama.

But it may be a mistake to imagine that the US and British bombing of Isis, when it is fighting the Syrian army, would simply secure Assad in power. The militarisation of politics in Syria since 2011 has benefited both Isis and Assad: it has left Syrians opposed to Isis and al-Nusra, but even more terrified of Assad’s forces, with no alternative but to fight and die with the jihadis. Likewise, if you are an Alawite, Christian, Druze or simply a Sunni working for the central government, you rightfully fear that if Assad goes down, so do you and your family who will lose their homes, jobs and possibly their heads. You will have heard the opposition slogan “Alawites to the cemetery and Christians to Beirut”. You will have no alternative but to stick with Assad.

Militarisation of politics in Syria has benefited both Isis and Assad (AFP) (AFP/Getty Images)

One initiative that might work would be for the US and Britain to offer to use airstrikes in combination with the Syrian army against Isis, but to make this conditional on the regime stopping its barrel bombing of rebel-held areas. This would be appealing to the increasingly desperate supporters of Assad and might be difficult for him to turn down. Once his supporters feel they are no longer fighting for their very existence – and people living in rebel areas feel the same way – then compromises and ceasefires begin to become feasible.