Almost exactly 10 years ago, a senior American diplomat looked out of his office window in Damascus and watched Syrian secret policemen brazenly set up a jihadi recruiting station right opposite the US embassy.

Bashar al-Assad’s regime, which had curried favour with Washington after 9/11 by sharing its files on Islamist radicals with the CIA, now decided it would funnel jihadi volunteers from across the Arab world into Iraq, to bleed the Anglo-American invasion and occupation.

No friend of al-Qaeda or Sunni radicalism, the Assad regime, built up over four decades around the heterodox Shia, minority Alawite community, has nevertheless always been flexible in its choice of guns for hire.

This week, al-Qaeda in Iraq announced that Jabhat al-Nusra – the Sunni jihadist front spearheading the fight against loyalist forces in northern Syria – had merged with it. The news has been contested, not least by Nusra itself.

But Assad regime hierarchs have in any case had plenty of time to parse the full meaning of “blowback”. The jihadis whose path Damascus smoothed into Iraq do not need any help, or indeed mergers, to find their way back. The tactical promiscuity of the Assads has always looked like a strategic liability.

Bad news for the Assad clan and its crumbling regime is not necessarily good news for Syrians and the future of their country, pulverised by two years of war.

Tuesday’s message, posted by the al-Qaeda front in Iraq, that “the Nusra Front is simply a branch of the Islamic State of Iraq”, as the US has long argued, is chilling, whether true or not. And the Nusra leader Abu Mohammed al-Joulani’s denial is hardly reassuring, given that he pledges allegiance to Ayman Zawahiri, global leader of al-Qaeda.

If the al-Qaeda worldview puts down roots in Syria – a tolerant if traditional society with a mosaic of religions, even if the Sunni are a majority – a rebellion to break free from tyranny could morph into another war between anti-Assad secularists and theocratic extremists.

Memories of what happened in Iraq loom large in Syria. The butchery of Abu Musab al-Zarqawi, the late al-Qaeda leader in western Iraq, unleashed ethno-sectarian carnage between Sunni and Shia (the majority in Iraq). Minorities such as the Christians were crushed between them until the Sunni tribes turned against the jihadis. Read more