This undated image posted on a militant website purports to show militants on the Iraqi side of the Syria-Iraq border in April.
AMMAN - Concerns that U.S. military intervention in Syria would prop up extremist groups affiliated with al-Qaeda were scoffed at Thursday by leaders of Syria's opponents to dictator Bashar Assad, though analysts warn Islamic extremists are growing.
"The American strikes are not to destroy the rebels, it is to destroy the regime," said Hozan Ibrahim, part of the opposition movement that includes the Free Syrian Army.
"Aside from some individual cases, the rebels didn't commit any massacres. And this is not definitely not Iraq, this is not Afghanistan," he said. "There aren't that many extremist groups - yet."
"Yet" is the point, analysts say. The longer the conflict drags on, the greater the chance that extremist groups expand in number and influence, said Jane Kinninmont, an analyst at the Chatham House think-tank in London.
"There are al-Qaeda elements active in Syria, although they weren't there at the beginning," Kinninmont said.
The Obama administration insists that the vast majority of rebels in Syria are Sunni Muslims seeking to end a tyranny, not impose Islamic law. But it admits that al-Qaeda loyalists who would do such things are operating in Syria.
"I just don't agree that a majority are al-Qaeda and the bad guys. That's not true. There are about 70,000 to 100,000 oppositionists. ... Maybe 15% to 25% might be in one group or another who are what we would deem to be bad guys," Secretary of State John Kerry said this week in testimony before Congress.
"There is a real moderate opposition that exists. Gen. Idriss is running the military arm of that," Kerry said in reference to Gen. Salim Idriss, head of the rebel Free Syrian Army that is made up of former Syrian soldiers and others.
He referred to a report from Elizabeth O'Bagy, an analyst with the Institute for the Study of War think-tank, which claimed that Islamic extremist factions are not "spearheading the fight against the Syrian government," but rather that the struggle is being led by "moderate opposition forces."
But in rebel-held Aleppo, the BBC reported that a 14-year-old boy was executed in public by Islamists for insulting Islam.
Extremist groups have released videos over the past few months in which they kill locals in towns they say have violated Islamic law. Assad said in an interview with the French newspaper Le Figaro that his fight is against terrorists.
"We are fighting terrorists. Eighty to 90% of those we are fighting belong to al-Qaeda. They are not interested in reform or in politics. The only way to deal with them is to annihilate them," he said.
Many Syrian fighters believe in some form of Islamic law, not an unusual stance in a Muslim country. But the uprising began in March 2011 as a challenge to the dictatorial policies of Assad, and peaceful demonstrations of Syrians called for democratic change, not Islamic law.
It was not until Assad responded by killing and arresting demonstrators that the opposition movement took up arms.
Kinninmont said the Syrian government has long been sending the message internationally that it is a force for stability and is keeping al-Qaeda and other sectarian ideological groups in check.
"It's quite ironic that the Assad government said that everyone opposed to them is a foreign-backed terrorist and over time, more foreign-backed terrorists have become involved," she said
Among the foreign fighters in Syria are groups such as Jabhat al-Nusra, which swears allegiance to al-Qaeda and is designated as a terrorist group by the United States. Also in Syria is the Islamic State of Iraq and the Levant, and jihadists from Chechnya, Pakistan and other countries have answered the call of al-Qaeda to fight Assad.
Al-Qaeda is a Sunni Muslim terror group that seeks to establish Islamic theocracies in all Muslim countries. Its adherents have shown up in many Arab states where uprisings have taken place, such as Yemen, Iraq and Egypt, and attempted to impose its authority.
In Syria, the extremists fight in their own units and sometimes coordinate their operations with the Free Syrian Army. They have taken control of the city of A Raqqa in the north of the country, instituting a council and sharia courts.
These extremist groups are better funded, equipped and trained than local fighters, says the Free Syrian Army, which itself is made up of hundreds of independent units. The extremist fighters have made headway in some areas of Syria such as Idlib province.
As a result, Syrians are leaving areas increasingly affected by extremist clashes for control over strategic areas close to the Iraqi border in droves. Last month, thousands of refugees fled escalating violence between extremist groups and Kurdish militias as well as the Free Syrian Army in northeastern Syria crossing into Iraqi Kurdistan.