The “Islamic State” is stronger than it was when it was first proclaimed on 29 June last year, shortly after Isis fighters captured much of northern and western Iraq. Its ability to go on winning victories was confirmed on 17 May this year in Iraq, when it seized Ramadi, the capital of Anbar province, and again four days later in Syria, when it took Palmyra, one of the most famous cities of antiquity and at the centre of modern transport routes.

The twin victories show how Isis has grown in strength: it can now simultaneously attack on multiple fronts, hundreds of miles apart, a capacity it did not have a year ago. In swift succession, its forces defeated the Iraqi and Syrian armies and, equally telling, neither army was able to respond with an effective counter-attack.

Supposedly these successes, achieved by Isis during its summer offensive in 2014, should no longer be feasible in the face of air strikes by the US-led coalition. These began last August in Iraq and were extended to Syria in October, with US officials recently claiming that 4,000 air strikes had killed 10,000 Isis fighters. Certainly, the air campaign has inflicted heavy losses on Isis, but it has made up for these casualties by conscripting recruits within the self-declared caliphate, an area the size of Great Britain with a population of five or six million.

What makes the loss of Ramadi and Palmyra so significant is that they did not fall to surprise attacks, the means by which a few thousand Isis fighters unexpectedly captured Mosul, Iraq’s second largest city, in 2014.

ORDER IT NOW

That city had a garrison estimated to number about 20,000 men, though nobody knows the exact figure because the Iraqi armed forces were full of “virtual” soldiers, who did not physically exist but whose pay was pocketed by officers and government officials. Baghdad later admitted to 50,000 of these. There were, in addition, many soldiers who did exist, but kicked back at least half their salary to officers on the condition that they perform no military duties.

Yet the outcome of the fighting at Ramadi, a Sunni Arab city which once had a population of 600,000, should have been different than at Mosul. The Isis assault in mid-May was the wholly predictable culmination of attacks that had been continuous in the eight months since October 2014. What was unexpected was a retreat that was close to flight by government forces and, in the longer term, the same old fatal disparity between the nominal size of the Iraqi armed forces and their real combat strength.

A crucial feature of the political and military landscape in Iraq is that the Iraqi army never recovered from its defeats of 2014. To meet Isis attacks on many fronts it had fewer than five brigades, or between 10,000 and 12,000 soldiers, capable of fighting while “the rest of the army are only good for manning checkpoints” – in the words of a senior Iraqi security official. Even so, many of these elite units, including the so-called Golden Division, were in Ramadi, though their men complained of exhaustion and of suffering serious casualties without receiving replacements.

In the event, even the presence of experienced troops was not enough. Just why the government forces were defeated is partly explained in an interview with The Independent by Colonel Hamid Shandoukh, who was the police commander in the southern sector of Ramadi during the final battle. Speaking of what happened to his detachment, the colonel says: “In three days of fighting, 76 of our men were killed and 180 wounded.” Isis commanders used a lethal cocktail of well-tried tactics, sending fanatical foreign volunteers driving vehicles packed with explosives to blow themselves up and demolish government fortifications. Suicide bombing on a mass scale, with explosions capable of destroying a city block, was followed by assaults by well-trained infantry, including snipers and mortar teams.

Col Shandoukh, himself a Sunni Arab, says the root of the problem is simply that neither the Iraqi security forces nor pro-government tribal forces received reinforcements or adequate equipment. He says that the central failure is sectarian and happened “because of [government] fear that, as the people of Anbar are Sunni, mobilising them will threaten the government later”.

He complains that sophisticated weapons are reserved for Shia militias and specialised counter-terrorism units, while the predominantly Sunni Arab police in Anbar received only seven Humvees, far fewer than the number captured by Isis in Mosul.

I am a little wary of Colonel Shandoukh’s explanation that Isis’s victory was thanks to superior weapons denied to his own troops by the Shia-dominated Baghdad government. Lack of heavy arms is an excuse invariably used by Iraqi and Kurdish leaders to explain reverses inflicted on them by inferior forces. But this claim is frequently contradicted by pictures and videos shot by Isis after it has captured positions, showing heaps of abandoned weaponry.

At Mosul last year and again at Ramadi almost a year later, there was the same breakdown in morale among government commanders leading to a panicky and unnecessary withdrawal. In the sour words of General Martin Dempsey, the chairman of the US Joint Chiefs of Staff “the Iraqi security forces weren’t “driven from” Ramadi, they “drove out of Ramadi”.

Colonel Shandoukh regards distrust between Sunni and Shia as the main cause of the rout. He argues that the people of Anbar, a vast province that makes up at a quarter of Iraq, are “looked at as terrorists by the government; even the Sunni military staff and their detachments are not given full support”. Others blame the corruption and overall dysfunctional nature of the Iraqi state in a country in which people’s primary loyalty is to their sectarian or ethnic community. Iraqi nationalism is at a discount.

A more precise reason for the military disintegration may be that Iraqi army, and this also applies to the Kurdish Peshmerga, have become over-dependent on US air strikes. In Iraqi Kurdistan, Peshmerga respond to Isis attacks by giving their exact location to the US-Kurdish Joint Operations headquarters in Erbil which calls in air strikes. Significantly, it was an impending sandstorm that would blind US aircraft and drones and prevent their use that was apparently the reason why the order was given for Iraqi forces to abandon Ramadi. Colonel Shandoukh says that “without US-led airstrikes, Ramadi will not be recaptured”.

General Dempsey’s ill-concealed anger at the debacle at Ramadi may stem from his understanding that the disaster involves more than just the loss of a single city, but discredits the whole American strategy towards Islamic State. The aim was to use US air power in combination with local ground forces to weaken and ultimately eliminate Isis. It was a policy that Washington had persuaded itself was working effectively right up to the moment it fell apart on 17 May.

Proof of this is a spectacularly ill-timed and over-optimistic briefing given on 15 May by Brigadier General Thomas D Weidley, the chief of staff for Combined Joint Task Force Operation Inherent Resolve, as the US-led air campaign to defeat Islamic State is known. “We firmly believe [Isis] is on the defensive throughout Iraq and Syria, attempting to hold previous gains, while conducting small-scale, localised harassing attacks [and] occasionally complex or high-profile attacks to feed their information and propaganda apparatus,” he said.

Gen Weidley revealed that the coalition had launched 165 air strikes in Ramadi over the previous month and 420 in the Fallujah-Ramadi area since the air campaign started, and sounded fully confident that these had stopped Isis’s run of victories.

Keep in mind that on the very day the General was making his upbeat remarks, Isis was over-running the last government strongholds in Ramadi. In other words, whatever the Pentagon thought was happening on the battlefields of Iraq and Syria was wrong. As in Korea in 1950 and South Vietnam in 1968, an enemy that the US military was convinced was on the run had suddenly struck back with devastating impact. The air strikes in the Ramadi area, and a further 330 in and around the Baiji refinery and town, did not prevent Isis concentrating its forces and launching a successful offensive.

The US generals were not alone in their over-optimism. The capture of Tikrit, the home city of Saddam Hussein, by the Iraqi army and Shia militias led to exaggerated assumptions worldwide that Islamic State was on the retreat. On 1 April the Iraqi Prime Minister, Haider al-Abadi, walked down the main street of Tikrit, basking in the plaudits of his triumphant troops. He later announced that “the next battle” would be for Anbar, a forecast that turned out to correct though not in the sense Mr Abadi intended – since it was a battle decisively won by Isis.

The loss of Ramadi has exposed Western policy for defeating Isis in Iraq as a failure and no new policy has been devised to take its place. If the same thing has not happened in Syria, it is simply because the West never had a policy there to begin with or, put more charitably, in so far as there was a policy, it was so crippled by contradictions as to rob it of any coherence or chance of success (something I will explore in a later article in this series).

The West would like to weaken President Bashar al-Assad, but is frightened that, if he goes, his regime will collapse with him and thereby create a vacuum which would be filled by Islamic State and by Jabhat al-Nusra, al-Qaeda’s Syrian affiliate, which leads a coalition of fundamentalist Sunni Arab rebel groups supported by Turkey, Saudi Arabia and Qatar.

Western-backed moderates play only a marginal role among the Syrian opposition fighters. Robert Ford, the former US ambassador to Syria, and a long-time supporter of the rebel moderates, changed his stance earlier this year announcing that the reality in Syria is that “the people we have backed have not been strong enough to hold their ground against the Nusra Front”.

Nevertheless, Western policy is to pretend that there is still a “moderate” alternative to Assad, whose forces are ebbing in strength. Both Assad, Islamic State and Jabhat al-Nusra benefit from the total militarisation of Syrian politics whereby no compromise is possible between the contending sides. A state of permanent war seems to be in their interests, since disaffected members of their own side have no alternative but to fight.

After capturing Palmyra, Islamic State is now threatening Deir Ezzor, a Sunni Arab tribal city, one of the few strongholds still held by the government in eastern Syria. Isis is getting closer to Aleppo, once Syria’s largest city, and probably hopes to take it at some point in the future. According to the Syrian Observatory for Human Rights, Islamic State “has seized more than 50 per cent of Syria and is now present in 10 of its 14 provinces”. It adds that Isis now holds the majority of Syria’s oil and gas fields.

This calculation gives a slightly exaggerated idea of Islamic state control in Syria since its dominance is mostly in the scantily-populated regions of the east. It is under pressure from the well-organised Syrian Kurds, fighting against whom it suffered its biggest defeat when it failed to take the city of Kobani despite a four-and-a-half month siege. On 16 June, Isis lost the important border crossing into Turkey at Tal Abyad after an attack by the Kurds backed by US air power. Earlier this week they were reportedly driven out of the town of Ayn Isa and a nearby military base, just 30 miles north of Raqqa, the Syrian city that is the Isis capital.

Once again, this led to over-optimistic talk of Isis weakening, though it did not try very hard to hold either town as they were encircled by Kurdish troops. As in Iraq, Kurdish willingness and ability to advance into Sunni Arab majority areas is limited so the Kurds will not inflict a decisive defeat on Islamic State. Yesterday there were reports of Isis advancing in other areas.

Isis has more long-term opportunities in Syria than Iraq because some 60 per cent of Syrians are Sunni Arabs, compared to only 20 per cent in Iraq. It has yet to dominate the Sunni opposition in Syria to the extent it does in Iraq, but this may come. As sectarian warfare escalates, Isis’s combination of fanatical Sunni ideology and military expertise will be difficult to overcome.