The year-long effort to overthrow President Bashar al-Assad and his government has failed. Two or three months ago, it seemed to come close to succeeding, as insurgents took over enclaves in cities such as Homs and Deir el-Zour. There was talk of no-fly zones and foreign military intervention.

Severe economic sanctions were slapped on Syria's already faltering economy. Every day brought news of fresh pressure on Assad and the momentum seemed to build inexorably for a change of rule in Damascus.

It has not happened. Syria will not be like Libya. The latest international action has been an EU ban on Assad's wife, Asma, and his mother travelling to EU countries (though, as a UK citizen, Asma can still travel to Britain). As damp squibs go, this is of the dampest. The Foreign Secretary, William Hague, claims this increases the pressure on the Syrian government but, on the contrary, it relieves it. Curtailing Asma's shopping trips to Paris or Rome, supposing she ever intended to go there, shows the extent to which the US, EU and their allies in the Middle East are running out of options when it comes to dealing with Damascus.

"Nobody is discussing military operations," the UN Secretary-General, Ban Ki-moon, said last week. The insurgent Free Syrian Army has been driven out of strongholds in the central city of Homs, Idlib province in the north and, most recently, Deir el-Zour, in the east. Last Tuesday, Syrian soldiers supported by tanks rolled from four sides into Deir el-Zour, which is about 60 miles from the Iraqi border, forcing the rebels to flee and take shelter in homes and apartments after a short gun battle. Their retreat may make it more difficult to bring guns across the Iraq border from the overwhelmingly Sunni Anbar province. The swift Syrian army advance was in contrast with the month-long siege of the Baba Amr district of Homs which killed hundreds of people and left much of the area in ruins. Saudi Arabia and Qatar have blithely advised arming the insurgents, but there is little sign of them doing so.

What went wrong for the advocates of regime change? In general, they overplayed their hand and believed too much of their own propaganda. By this January, everything they did was predicated on international military intervention, or a convincing threat of it. But this ceased to be an option on 4 February when Russia and China vetoed a UN Security Council resolution, backed by the Arab League, calling on Assad to step down. The experience of the US, EU, Nato and the Arab Gulf states in overthrowing Muammar Gaddafi turned out to be misleading when it came to Syria.

This has been the experience of revolutionaries and counter-revolutionaries throughout the ages. What succeeds in one country proves a recipe for disaster in another. There was also a misreading of what had happened in Libya. Watching al-Jazeera television, it might appear that heroic rebel militiamen – and at times they were heroic – had overthrown a tyrant but, in reality, military victory was almost wholly due to the Nato air assault. The militiamen were a mopping-up force who occupied territory after air strikes had cleared the way (this was also the pattern in Afghanistan in 2001 and in Iraqi Kurdistan in 2003).

Conditions are very different in Syria. The regime has a radicalised core based on the Alawite community, a powerful army and security forces. There have been few high-level defections or military units changing sides. Regime loyalists feel they have no alternative but to fight to the end, and are quite prepared to kill anybody who gets in their way. Economic sanctions do not worry Assad loyalists because a dictatorship can always commandeer resources even when they are reduced in quantity. Assad has already lost the support of most of the Syrian business community. Militarisation of the conflict does not pose a threat to the government at this stage; it is more of an irritant, though this could change if guerrilla warfare develops.

In the second half of last year Assad appeared to be facing an all-powerful international coalition. It included Saudi Arabia and Qatar, the US, EU and Turkey. It emerged, however, that everybody was in favour of somebody doing something to bring him down – so long as that somebody was somebody else. There was talk of "safe havens" being established on the Jordanian or Turkish borders, but neither Jordan nor Turkey showed any enthusiasm for an act that would lead immediately to armed conflict with Syria. King Abdullah of Jordan said ruefully that he had nothing against "safe havens" so long as they were a long way from Jordan. Turkey cooled on the idea as it became apparent that it was becoming embroiled in a regional Shia-Sunni conflict that would lead to Iran retaliating against Turkey in defence of its Syrian ally.

The Syrian protesters did everything they could to give the impression that what happened in Libya could be repeated in Syria. They are now being criticised for their divisions and lack of leadership, but probably they felt they had no choice. The uprising had begun among the under-class of Syrians, but by last summer had spread to the middle class. But the use of snipers and death squads by the regime made street protests highly dangerous and they have got smaller in recent months (one of the benefits of the Arab League monitoring team was that it opened the door again to street demonstrations). Protesters now seldom wave olive branches and chant "Peaceful, Peaceful". Militarisation of the protest movement and the increased sectarianism played to the strengths of the regime. Sectarianism not only weakens the opposition inside Syria, it helps divide the coalition facing it abroad. In a presidential election year, US voters do not care much who rules Syria, but they care a lot about al-Qa'ida.

One of Barack Obama's themes in the presidential campaign will be that it was his administration that killed Osama bin Laden and focused, unlike President Bush, on eliminating the perpetrators of 9/11. The White House does not want al-Qa'ida to show signs of life, so it has been nervous of its increasing role in Syria. For instance, only last week an al-Qa'ida-inspired group called the Al-Nusra Front to Protect the Levant claimed responsibility for two recent suicide bombings in Damascus that killed more than two dozen people. "We tell the [Syrian] regime to stop the massacres against the Sunnis, otherwise, you will bear the sin of the Alawites," said the Al-Nusra Front statement. "What is coming is more bitter and painful, with God's will."