The British Government’s fawning on the absolute monarchs of the Gulf, whose authority is enforced by beheadings, lashings and the torture chamber, is at once contemptible and pathetic. It is a measure of Britain’s decline as a great power that it is only in tiny, toxic, sectarian Bahrain, where Sunni rulers suppress the Shia majority, that Theresa May can expect a regal reception.

May added her own few drops of venom to the raging sectarian warfare between Sunni and Shia in the region by targeting Iran. She said she was “clear-eyed” about the Iranian threat to an audience of largely fundamentalist Sunni Gulf leaders for whom the words “Iran” and “Shia” are demonic and interchangeable.

In Bahrain, the monarchy blamed the peaceful democratic uprising during the Arab Spring in 2011 on a deep-laid Iranian plot.

I spoke later the same year to doctors who had worked in a hospital in central Manama, the Bahraini capital, where they had treated injured protesters. After the demonstrations were crushed with the backing of Saudi troops, the doctors had been savagely tortured for using a complex piece of medical equipment that the Bahraini security forces had convinced themselves was the means by which Iran gave the protesters their instructions. It is this type of paranoia that May is feeding, though an independent inquiry found no evidence of Iranian involvement in the protest movement.

In pictures: Aleppo bombing Show all 14 1 /14 In pictures: Aleppo bombing In pictures: Aleppo bombing Bombing in Aleppo Smoke rises after airstrikes on the rebel-held al-Sakhour neighborhood of Aleppo, Syria April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian family runs for cover amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighbourhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo A man reacts as he stands on blood stains at a site hit by airstrikes in the rebel held area of Aleppo's al-Fardous district, Syria, April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo The damage of the airstrikes in the rebel-held area of Aleppo on April 28 Reuters In pictures: Aleppo bombing Bombing in Aleppo The damaged the Medecins Sans Frontieres (MSF)-backed al-Quds hospital after it was hit by airstrikes, in a rebel-held area of Syria's Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo Syrians evacuate an injured man amid the rubble of destroyed buildings following an air strike on a rebel-held of Aleppo on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo People inspect the damage at a site hit by airstrikes, in the rebel-held area of Aleppo's Bustan al-Qasr AP In pictures: Aleppo bombing Bombing in Aleppo A man leads a woman in tears and child out of the scene after airstrikes hit Aleppo AP In pictures: Aleppo bombing Bombing in Aleppo Civil defence members search for survivors after an airstrike at a field hospital in the rebel held area of al-Sukari district of Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian boy is comforted as he cries next to the body of a relative who died in a reported air strike in the rebel-held neighbourhood of al-Soukour in the northern city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo A Syrian family walks amid the rubble of destroyed buildings following a reported air strike in the Bustan al-Qasr rebel-held district of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers and rescuers remove a baby from under the rubble of a destroyed building following a reported air strike on the rebel-held neighbourhood of al-Kalasa in the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers evacuate people from a damaged building following a reported airstrike in the rebel-held neighbourhood of Tareeq al-Bab in the northern city of Aleppo

Downing Street’s rebuttal of Boris Johnson’s demonstrably correct view that Saudi Arabia wages “proxy wars” in the Middle East is equally mendacious. Turkey, Saudi Arabia and Qatar have taken a leading role in funding and supplying weapons to extreme jihadi insurgents in Syria, as US leaders – including President Obama and Vice President Joe Biden, supplemented by leaked documents – have made clear.

The Saudi intervention in Yemen, where airstrikes have devastated a country of 25 million people, differs only from its other interventions in that the Saudi role is overt and the suffering even more massive.

The humiliating and discreditable British posture in the Gulf is presumably a desperate attempt to find new allies in the run-up to Brexit. This might seem to be a good moment to do so, since the winners and losers in the wars that have engulfed Syria and Iraq over the last five years are becoming apparent. The only surprising aspect of the British initiative is that we seem, as we did in Iraq and Afghanistan, to be joining the losing side.

It is a moment of decision in Syria as the Syrian Army and its allies are close to overrunning east Aleppo, the last big urban enclave of the armed opposition. Their victory means that President Bashar al-Assad will stay in power, something that his many enemies were prone to discount until recently. Touchingly out of date with these developments on the battlefield, British policy remains that Assad must go before political progress is possible.

A similarly decisive moment has arrived in Iraq, though the security forces are making slower progress than in Aleppo in driving Isis from Mosul east of the Tigris River. Isis is deploying mobile squads of experienced fighters hidden in a vast network of tunnels backed up by hundreds of suicide bombers, snipers and mortar teams. The Iraqi security forces have lost almost 2,000 soldiers in November, according to the UN, but the superior firepower and numbers of the Iraqi government backed by the US-led air coalition are likely to overwhelm Isis in the long-run.

The victories of Assad and the Baghdad government will determine the political landscape of the Middle East for decades to come. The wars have been so long and so savage because Syria and Iraq have provided the battlefield on which more than half a dozen powers have fought out their differences. Since the second half of 2011, the advance and retreat of all sides in Syria has been determined by how much support they could get from their outside backers – Turkey, Saudi Arabia and Qatar for the insurgents and Russia, Iran, Iraq and Hezbollah for Assad – in terms of men, money, arms, ammunition and airstrikes.

It is a regional war and its outcome will affect the whole area from Pakistan to Nigeria, as well as being a sectarian conflict, primarily but not exclusively between Sunni and Shia, which impacts on all the 1.6 billion Muslims in the world.

Islamic State video purports to show fighting in Mosul

But how can we be sure that we are seeing a turning point in such a complex battle involving so many players with such divergent interests?

Isis and the armed opposition in Syria, led by Jabhat al-Nusra, formerly the al-Qaeda affiliate, fight quasi-guerrilla campaigns in which the loss or gain of territory does not necessarily tell one who is winning. The crucial change in the battle for east Aleppo is essentially political. Nusra, Ahrar al-Sham and the core fighting units have received little help, verbal or physical, from their former sponsors in Turkey, Saudi Arabia and Qatar. If these three did not support the rebels while they still held east Aleppo, it is unlikely that they will do so after the rebels have lost it.

The romantic image of heroic guerrillas standing alone anywhere in the world has always understated the degree to which they depend on outside powers. Possibly, the Turks and Saudis could sustain low level guerrilla warfare against Assad for a long time, but they would risk retaliation from victorious governments on the Shia side.

Foremost among the losers in this war are the Sunni Arab communities in Iraq and Syria, who have been defeated in their long struggle for power with the Shia and Kurds. Syrian exiles and their media sympathisers play down the sectarian and ethnic nature of the conflict, just as the Shia and Kurdish exiled opposition from Iraq did before the US-led invasion of 2003 in order to lure the US into overthrowing Saddam Hussein. “We are going to be the new Palestinians,” a young Sunni journalist from the city of Ramadi in Iraq lamented to me, shortly before 70 per cent his city was destroyed by US airstrikes and Iraqi Army artillery.

Iran is a winner in this historic conflict so far. It was the essential ally of Assad from 2011 to 2015, when Russia intervened militarily with its air force. The fear of extermination by Isis and al-Qaeda clones forced Shia communities together, including those with very different theologies. Overall, Iranian and Russian determination to support Assad was always deeper than that of the opposing alliance of Sunni states led by Turkey and Saudi Arabia, which replaced Qatar as the principal foreign backer of the Syrian insurgents in 2013.

Russia has re-established itself as a great power, if not a superpower, through the Syrian war. This was an ideal conflict for Moscow because Assad was always stronger and his domestic opponents weaker than they looked. President Putin did not have to deploy enormous resources to make a decisive difference. Though Putin is much demonised in the West, the enthusiasm of Western governments to get rid of Assad has ebbed steadily, as it became clear that the only alternative to him was Isis or Nusra.

Theresa May: Islamic State's days as occupying force numbered

Governments and public in the Middle East tend to exaggerate or understate American power in the region. In reality, the US position remains strong, with every Iraqi unit approaching Mosul including a US soldier calling in airstrikes while, behind the scenes, the US is orchestrating the logistics for the entire operation. In Syria, the US military alliance with the Kurdish paramilitaries has been highly effective in driving back Isis and closing the border with Turkey.