The Islamist uprisings in Iraq and Syria have the world's counterterrorist agencies worried. Thousands of disenchanted young Sunni Muslims from Asian and Western countries have joined the battle for a state stretching from southern Turkey to Egypt. There are justifiable fears that they will return home as combat-hardened extremists, eager to broaden their struggle. Never was there a more pressing need for governments to work together to counter the threat.

Intelligence officials believe 12,000 Muslims from 81 countries from Australia to Europe and North America have joined the jihadists. Most are from the Arab world, with 3,000 from Tunisia and 1,500 from Morocco. But 3,000 are from Western countries, led by France with more than 700, Britain with at least 400, Germany 270 and Belgium with 250. Another 700 are from Russia and Muslims from Indonesia, Pakistan and China's autonomous region of Xinjiang are also thought to be involved. But the numbers are estimates based on people authorities have been able to track, and could be higher.

Counterterrorism experts are worried because of the lesson of the Soviet invasion of Afghanistan in 1979, which drew 10,000 foreign fighters over a decade. The struggle by Muslims to win back the country turned it into an incubator for extremist thought and terrorism. Al-Qaeda and other terror groups behind the wave of Islamist violence around the world in the 1990s and 2000s gained willing recruits from fighters who had combat experience, learned bomb-making skills and been exposed to extremist ideology. The push by al-Qaeda-inspired groups to topple the governments of Iraq and Syria are creating a worryingly similar scenario.