ISTANBUL // The recent public pledge of loyalty to Al Qaeda by the Nusra Front not only shocked the Syrian opposition, it also took some members of the Islamist rebel group by surprise, sparking an internal debate about how wise a move it was.
According to a Nusra militant in Damascus, he and fellow group members were blindsided by the announcement that they would follow the orders of Ayman Al Zawahiri, Osama bin Laden's successor as head of Al Qaeda.
"Honestly, everyone I know was surprised by the statement; it was more than we'd expected to hear," he said, hinting at sensitivities, if not outright tensions, within the secretive group.
The militant, a university-educated Syrian in his 30s, has been in the Nusra Front for more than a year. He was not involved in "senior management", he said, describing his role as logistics and surveillance, including tracking regime security officials in Damascus who have been deemed targets for assassination.
Group members knew that its leaders - some were Tunisian, Jordanian, Iraqi and Syrian, he said - had fought under the Al Qaeda banner in Iraq.
Nonetheless, he questioned the wisdom of making a public declaration of loyalty to Al Qaeda, saying it risked opening a dangerous rift with the Free Syrian Army (FSA), which has the backing of western and Arab states and with which Nusra has had a more-or-less cooperative relationship in their war against Bashar Al Assad.
"We are now concerned there will be clashes between us and the FSA," he said.
"We will not fight the FSA even if they come to fight us; touching the FSA is a red-line issue, we are all fighting to get rid of Assad and we should do that together."
His worry was shared by a leading member of Liwa Al Islam, a rebel group in Damascus fighting as part of the Syrian Islamic Liberation Front, a coalition that has publicly criticised the Nusra-Al Qaeda tie-up.
"There is a possibility for clashes between Nusra and other rebels, even Islamic groups - especially ones that have a more Sufi background, and we are seeing more and more points where sectarian problems are coming up," he said.
Sufism, a tolerant, mystical form of Islam, is typically at odds with the hardline interpretations of Salafis and Al Qaeda-affiliated groups.
The Liwa Al Islam fighter said his group continued to respect the Nusra Front and would keep co-operating with it. "If we ever need help we can ask them and they give it," he said. "They are very secretive, it's hard to know what they are planning and they never ask us for anything."
According to the Nusra member in Damascus, some inside the group had suggested that another public announcement be made to clarify the question of the group's links to Al Qaeda in an effort to defuse the issue.
His comments appeared to confirm a report last week by Al Jazeera, the Doha-based satellite news channel, which cited sources close to the group as saying they did not rule out "separations" unless the Al Qaeda controversy was quickly contained.
The militant in Damascus said winning over the public should remain a priority for the Nusra Front, which is one of the most effective and powerful Syrian rebel factions.
"Our power comes from the support we have from Syrian civilians," he said. "We respect civilian lives: we have called off many attacks and changed many plans because there would have been too many civilians killed."
Al Qaeda, not least its affiliate, the Islamic State in Iraq (ISI), is notorious for killing civilians in indiscriminate attacks. The Nusra Front appears to have been trying to distance itself from that reputation, which in part explains the recent public spat between it and the ISI.
On April 10, the ISI head, Abu Bakr Al Baghdadi, announced that it was merging with the Nusra Front to create a new organisation, to be named the Islamic State in Iraq and the Levant.
It was the first formal affirmation of widely suspected links between the groups, both of which are classified as terrorist organisations by the United States.
But the day after the ISI announcement, the Nusra Front's leader, Abu Mohammad Al Jolani, issued a statement saying the merger had not actually happened.
In the statement posted on the internet, Mr Al Jolani was, however, explicit in aligning the Nusra Front with Al Zawahiri and, by extension, with Al Qaeda.
He described him as the "sheikh of jihad", pledged Nusra's allegiance and promised to "listen to and follow his orders in hijra and jihad", providing they did not entail "blasphemy".
According to the Nusra militant in Damascus, it was that crucial paragraph that caught them unawares.
"The statement was what we had been told, right up until near the end when Zawahiri was mentioned; that was a surprise, we had not been told that was going to happen," he said.
Most of the statement was an assertion of Nusra's respect for, alliance with, but ultimately, independence from, the ISI.
Mr Al Jolani even appeared to suggest that, while ideologically the group shared Al Qaeda's desire to create a pan-Islamic state, it would not adopt the bloodier tactics of other Al Qaeda affiliates.
"Rest assured that what you saw from the Front in its defence of your religion, blood and honour and its good manners with you and the fighting factions will remain the same," he said.
The statement was seized upon by the Syrian regime, which touted it as proof of its claim to be fighting "terrorists", rather than suppressing a popular uprising that turned militant only in response to the security forces' use of deadly violence against unarmed protesters.
In the West it has added fuel to the debate about whether not intervening militarily to protect activists from regime attack, has worked to the advantage of Al Qaeda-inspired groups, with Islamic militants and weapons flooding in to fill the vacuum.
Why Mr Al Jolani decided to make such an explicit reference to Al Qaeda remains unclear.
The Nusra militant in Damascus said it might have been a way of contrasting Al Qaeda's role in helping Syrians with the international community's lack of action.
"The US and the West have done nothing for the Syrian people, while we are there helping them, so that should make people think about who their real friends are," he said.