It was some six months ago that Syrian rebel commanders met US intelligence officers in Jordan to discuss the status of the war and, the rebels hoped, to secure supplies of the sophisticated weapons they need to overthrow President Bashar Al Assad.
But according to one of the commanders present at the meeting, the Americans were more interested in talking about Jabhat Al Nusra, the Al Qaeda-affiliated group waging war on the Syrian regime than they were in helping the rebels advance on Damascus.
The commander - a moderate Sunni and an influential rebel leader from Damascus who said he has met intelligence operatives from Western and Arab states - said the US officials were especially keen to obtain information about the identities of Al Nusra insurgents and the locations of their bases.
Then, by the rebel commander's account, the discussion took an unexpected turn.
The Americans began discussing the possibility of drone strikes on Al Nusra camps inside Syria and tried to enlist the rebels to fight their fellow insurgents.
"The US intelligence officer said, 'We can train 30 of your fighters a month, and we want you to fight Al Nusra'," the rebel commander recalled.
Opposition forces should be uniting against Mr Al Assad's more powerful and better-equipped army, not waging war among themselves, the rebel commander replied. The response from a senior US intelligence officer was blunt.
"I'm not going to lie to you. We'd prefer you fight Al Nusra now, and then fight Assad's army. You should kill these Nusra people. We'll do it if you don't," the rebel leader quoted the officer as saying.
What the commander says transpired in Jordan illustrates a dilemma that has preoccupied, even paralysed, Syria's opposition and their international supporters - how to deal with the expanding role of Islamic extremists in the anti-Assad insurgency.
Other meetings with Western and Arab intelligence services have shown a similar obsession with Al Nusra, the commander said.
"All anyone wants is hard information about Al Nusra, it seems to be all they are really interested in. It's the most valuable commodity you can have when dealing with these intelligence agencies," he said.
Jabhat Al Nusra has emerged as the most effective rebel force in Syria. The fractured, poorly equipped rebels of the Free Syrian Army can ill-afford to take the fight to Mr Al Assad's forces without Al Nusra, whose key leaders are foreign veterans of the fighting that followed the US invasion of Iraq in 2003.
The Obama administration classified Al Nusra as a terrorist organisation in December, much to the annoyance of the opposition Syrian National Coalition (SNC), which said the designation would only undermine the rebel campaign and support Mr Al Assad's insistence that he is fighting "terrorists" rather than a popular, pro-democracy uprising.
Two months ago, Al Nusra confirmed its link to Al Qaeda, publicly declaring "allegiance" to the network's head, Ayman Al Zawahiri, and promised to follow his orders.
Ever since, opposition political and military leaders, and their supporters in Europe, the US and the Middle East, have been trying to work out how to deal with the fact their allies on the battlefield are affiliated with the group that carried out some of world's deadliest attacks on civilians.
As the rebels and their patrons abroad debate how to deal with Al Nusra, questions persist over exactly how united Al Nusra is, and whether or not it has adopted a new, less violent, strategy than that normally associated with Al Qaeda.
While key Al Nusra leaders are foreign fighters bloodied in Iraq's sectarian civil war, a majority of the group's rank-and-file are Syrians, some of whom have expressed dismay about the pledge to Al Qaeda.
On Saturday, another major hardline Islamic faction, Ahrar Al Sham, issued a respectfully worded statement rebuking Al Nusra for openly siding with Al Qaeda, saying it was divisive and would not help the rebels win - although it supported the principle of a pan-Arab Islamic state.
Those within the moderate opposition advocating dialogue with Al Nusra warn that merely dismissing all of its fighters as hard-core radicals is a dangerous oversimplification.
It also risks alienating the many ordinary Syrians in rebel-held areas who have come to admire the group, with its reputation of honesty, discipline and provision of humanitarian supplies to those in need.
"There are very localised differences between rebel groups, and Al Nusra is no exception. Some are more extreme than others, and it's not right or useful just to put them all together as being Al Qaeda," said a moderate, Western-educated pro-democracy activist who has been involved in meetings with Nusra fighters in northern Syria.
Syria's political future was discussed at the meetings, and Nusra members were open to debate and discussion, and had shown interest in proposals about democracy and safeguarding Syria's minority communities, activists said.
"When you actually sit down with them [Al Nusra], you realise they are not what you thought and they also have to rethink their own preconceptions. We had a meeting and it was very good and these young fighters were surprised because they thought all people who supported democracy were atheists," the activist said. "For those reasons, it's important to keep a dialogue going."
Another Assad opponent, a secular Syrian involved in organising armed groups in Damascus, also warned against ignoring the differences within Al Nusra.
Comparing the situation in Syria to that in Afghanistan, he said the reach of Al Qaeda had always been held in check because they were foreigners not locals. The Americans, he said, made a mistake by waging war on the Taliban, with whom the Afghan authorities are now trying to negotiate.
"I am worried about Islamic extremism, but I think we need to be smart in how we handle it. Otherwise we'll make matters worse, not better," he said. "In the end this should be a matter for Syrians to resolve, it's not for the West to tell us who are terrorists and who are not."
The rebel commander who described meeting US intelligence officers in Jordan said he had refused to give them any information about Al Nusra.
Although not a supporter of Al Qaeda's ideology, he said the Americans were being too clumsy and would only undermine the revolt against Mr Al Assad.
"There are three strands of Al Nusra - the minority are serious Al Qaeda people, some are just in for the glamour of fighting jihad and the majority are ordinary Syrians who just want to save their country," he said.
Since that meeting the rebel commander has not bothered to talk to Western or Arab intelligence agencies, despite what he described as frequent invitations for more talks. Rather than wait for foreign governments to supply weapons, his group has imported their own advanced explosives and begun manufacturing their own munitions.
"They [foreign governments] are not fighting for the same things as us," he said. "Syrians are fighting for our freedom, while they just want us to bleed to death fighting each other."