Reuters reports: Abu Bakr, a Syrian rebel commander on the outskirts of Aleppo, is a devoted Islamist determined to overthrow President Bashar al-Assad. But the radical allies that have joined the rebels in recent months alarm even him.

“Let me be clear. I am an Islamist, my fighters are Islamists. But there is more than one type of Islamist,” he told Reuters. “These men coming fought in insurgencies like Iraq. They are too extreme, they want to blow up any symbol of the state, even schools.”

Seventeen months into the uprising against Assad, Syria’s rebels are grateful for the support of Islamist fighters from around the region. They bring weapons, money, expertise and determination to the fight.

But some worry that when the battle against Assad is over they may discover their allies – including fighters from the Gulf, Libya, Eastern Europe or as far as the Pakistan-Afghanistan border area – have different aims than most Syrians.

“Our goal is to make a new future, not destroy everything,” Abu Bakr said, sighing as he rattled his prayer beads. “As bloody as it is now, this stage is simple. We all have the same cause: topple the regime. When Bashar falls, we may find a new battlefront against our former allies.”

Abu Bakr and his comrades say they envision Syria as a conservative version of Turkey’s moderate Islamist rule, not an autocratic theocracy. They are unnerved by a recent kidnapping of foreign journalists and attacks on state infrastructure.

Western powers have warily watched the signs of an increasing presence of foreign Sunni Islamist fighters in Syria.

They fear a repeat of the mass sectarian slaughter that followed the American invasion of Iraq. Sunni Islamist suicide bombers affiliated with al Qaeda there are still targeting security forces and Shi’ites in large-scale bomb attacks.

Some fighters who have come to Syria are idealists who believe in jihad, or holy war, for oppressed Muslims, and would probably return home in a post-Assad era. But others are al Qaeda-linked fighters who may want a base in Syria.

Their numbers are still low, but enough to worry countries fearing Iraq-style bloodshed in Syria, a country straddling the lines of most ethnic and regional conflicts in the Middle East.