Omar Khatib began his conversation with International Business Times last April with this disclaimer: “I am not a terrorist. I just wanted to tell you that.” Khatib, who preferred not to disclose his real name for security reasons, had reason to be cautious -- the Syrian rebel had just returned from battle in the northwestern province of Idlib, roughly 22 miles from the Turkish border, where his militant brigade, Ahrar al-Sham, had recently partnered with Jabhat al-Nusra, a jihadist group affiliated with internationally designated terrorist organization al Qaeda.

The groups had joined together to fight the Syrian regime. Ahrar al-Sham and Jabhat al-Nusra “are two with one heart,” Khatib told IBTimes. Since then Ahrar al-Sham has become the strongest non-jihadist opposition force battling both the regime and the Islamic State group -- and they have Turkey’s support to thank for much of their success.

For four years, Turkey, a major NATO ally and an important member of the U.S.-led coalition targeting the Islamic State group in Syria, sat quietly, hoping Syria’s civil war would burn itself out before the government was prompted to openly support a side. But after a suicide bomber associated with the Islamic State group killed 31 people in the Kurdish-majority Turkish town of Suruc, Istanbul was forced to react.

In the days following the bombing, the U.S. and Turkey agreed to create a so-called safe zone in Syria along the Turkish border. Syria’s “moderate” rebels, as determined by the U.S., would clear ISIS militants from the area and allow Syrian refugees to return home. But Turkey had plans to include Ahrar al-Sham. Last week the Turkish government reportedly appointed the group as its negotiator for a temporary ceasefire in Syria.

Turkey “seems to have chosen a house to [publicly] back in Syria,” said Jennifer Cafarella, a Syria analyst at the Institute for the Study of War. “Ankara has worked closely enough with Ahrar — empowering the group not just as a fighting force, but also as a political actor — that Ankara has assumed a degree of ownership over Ahrar’s overarching political project,” War on the Rocks reported last week.

Turkey’s involvement with Ahrar al-Sham goes back several months earlier when Jaish al-Fatah, the "Army of Conquest” coalition, was formed in March by Nusra and other rebel groups fighting the regime. Turkish officials admitted giving logistical and intelligence support to the alliance’s command center but denied giving direct help to Nusra.

Ahrar, meanwhile, is adamant that the group is neither under Nusra’s control nor affiliated in any capacity other than through shared military headquarters. But this is not enough to convince the U.S. to back a brigade that works alongside a terrorist organization. “The question of its al Qaeda connections needs to be addressed,” Cafarella said. “The fact that that’s even a question indicates that they are not the group the U.S. coalition should be partnering with.”

The U.S. “neither worked with nor provided any assistance to Ahrar al-Sham” State Department spokesman John Kirby said in an email statement to IBTimes. Although Ahrar al-Sham is not on the U.S. designated terrorist list, the State Department “continues to have concerns with regard to the group’s relations with extremist organizations.”

Ahrar has been quick to downplay any links to extremism. When Turkey’s stance on Syria changed after the bombing, so did Ahrar’s. The group began marketing itself as an independent Syrian rebel group with the capacity to topple Syrian President Bashar Assad’s regime, defying Nusra’s ban on cooperating with Turkey because of its Western affiliations.

“We are not related with al Qaeda, we only fight with them against Assad and ISIS,” Ahrar’s political spokesman told IBTimes.

But others aren’t so sure. Ahrar shares many of the the same goals as al Qaeda, and a similar Islamist ideology. “Ahrar al-Sham isn’t going to abandon Nusra anytime soon or abandon the ideology,” Cafarella said. At least one Nusra fighter in Syria told IBTimes that he is optimistic for future military alliances between the two groups. Though there are currently no agreements between the two with regards to the future buffer zone, future deals are possible, he said.

But on Monday, Ahrar denied any affiliation with “any foreign parties including al Qaeda” in a statement released on their website. Cooperation with Turkey is based solely on Turkey’s support of Syria’s revolutionaries, the statement said.

Days before, a spokesman for Ahrar’s political office told IBTimes that the group is “ready to cooperate and coordinate with any country that wants to help our revolution honestly,” but that these are alliances of convenience and does not mean they are “an ally or proxy.”

The same logic could apply to Ahrar’s relationship with al Qaeda. Ahrar al-Sham has never been an official al Qaeda branch and both sides are happy to keep it that way knowing that NATO member countries, including Turkey, will never publicly support an al Qaeda faction.

This strategy allows the terrorist organization to have the de facto backing of regional powers and allows Ahrar to receive international support while accepting Nusra militants by the back door if necessary.

Ahrar al-Sham announced Monday it was recruiting fighters to institute a “reorganization of its military wing into a core, organized army.” Anyone is welcome to enlist, as long as they are devoted to Islam, of an “appropriate age” and in good health, according to a leaked statement from the group disseminated over social media.

“If something happens to Nusra we can accept their fighters in our ranks but on the conditions that they should forget al Qaeda,” Ahrar’s political official told IBTimes.

Even if Nusra and Ahrar end their alliance, Ahrar’s ties to al Qaeda predate Nusra. “Ahrar al-Sham was al Qaeda’s first play in Syria,” said Thomas Joscelyn, a senior fellow at the Foundation for Defense of Democracies and senior editor of the Long War Journal.

One of Ahrar al-Sham’s founding members was Mohamed Bahaiah, better known as Abu Khalid al-Suri, a suspected member of al Qaeda faction in Afghanistan with close ties to al Qaeda leader Ayman al-Zawahiri.

“U.S. officials say that he [Suri] is part of a secretive al Qaeda cadre that has sought to influence or co-opt parts of the Syrian insurgency that are not official al Qaeda branches,” the Long War Journal reported in 2013.

In 2014, Zawahiri reportedly appointed Suri as a mediator between Nusra and ISIS. Experts and sources close to both groups agree that Suri -- and therefore Ahrar -- was influenced by al Qaeda ideology even if it remained a distinct organization.

Suri is believed to have been killed by ISIS in February 2014. Today, Ahrar al-Sham claims that Suri’s ties with the al Qaeda leader were merely a “friendship,” but as the stakes grow higher in Syria, Ahrar al-Sham’s loyalties are likely to be tested.

“Friendship does not make you belong to the friend,” Ahrar’s political official told IBTimes.