A frozen conflict deep in the Caucasus warmed up last week when Azerbaijan launched a military campaign to wrestle back Nagorno-Karabakh, a contested territory held for years by Armenian forces. 

The conflict has pitted Armenia against Azerbaijan since the early 1990s, when the region was captured by local ethnic Armenians. However, the conflict has witnessed a new feature develop for the first time since it erupted nearly three decades ago. 

Turkey — a country that has long held affinities for Azerbaijan and its predominantly Turkic population — reportedly deployed Syrian mercenaries to bolster Azerbaijani forces, according to Armenian authorities. 

"Turkish military experts are fighting side by side with Azerbaijan, who are using Turkish weapons, including UAVs and warplanes," said the Armenian Foreign Ministry. "According to credible sources, Turkey is recruiting and transporting foreign terrorist fighters to Azerbaijan." 

Serving Turkey's interests abroad

The Syrian mercenaries have served Turkey's interests well as they offer a way to shore up its foreign policy objectives without mobilizing national assets such as the armed forces.

"They are an effective means to an end in providing Turkish President Recep Tayyip Erdogan with a military force that could be discarded once its usefulness has been completed," said Noah Agily, a Washington-based independent researcher focusing on militia recruitment and formation in Libya. "In the future, these mercenaries will allow Turkey to continue positioning itself geo-strategically without incurring domestic blowback."

But Agily sees the use of mercenaries as part of a wider trend for countries such as Turkey and Russia to bolster their interests in the Middle East, North Africa and beyond.

"Wars between states are becoming rarer, and instead, violent confrontations between non-state actors in spaces beyond state reach or in fragile governance areas will become more common.

Read more: Turkey's strategic play in Libya to help reap economic gains

Syrian mercenaries in Libya

It is not the first time that Turkey has been accused of sending Syrian mercenaries to distant lands to fight for its interests alongside military personnel.

Earlier this year, reports emerged that Turkey was using battle-hardened mercenaries from Syria to support the UN-backed Government of National Accord (GNA). Estimates placed the deployment of Syrian mercenaries in Libya at more than 3,000 — and some as high as 6,000.

Experts told DW that the presence of Turkey-backed Syrian mercenaries in Libya had effectively tipped the balance for pro-GNA forces. The alleged operation in Azerbaijan shared hallmarks of the Libyan escapade. 

"Many of the mercenaries were highly experienced fighters of grueling urban combat fought in Aleppo, Hama, Idlib and, more recently, as paramilitary operatives against the Kurds in northern Syria," said Agily.

"Using the Syrian mercenaries as ground operational forces and supporting them with drones operated by Turkish personnel allowed GNA's forces to stem the tide of the war and gradually contributed to the Libyan National Army's retreat to Sirte and Jufra in eastern Libya."

Read more: Libya: Are Turkey's Syrian mercenaries a new threat?

Murky origins

Although their precise origins remain unclear, the Syrian mercenaries recruited by Turkey appear to be a mix of former opposition fighters, militants and even refugees. 

In 2018, Turkish forces recruited Syrian opposition fighters operating under the banner of the Free Syrian Army (FSA) and used them for military campaigns against Kurds in northern Syrian. Reports a the time suggested that some of those fighters had been involved in violent extremist groups.

Meanwhile, the UK-based Syrian Observatory for Human Rights claimed that Turkish-backed Syrian mercenaries were former militants who fought for the likes of "Islamic State" and al-Qaida-affiliated militant groups.

But a US Department of Defense quarterly report conducted by the Office of the Inspector on counterterrorism efforts said in July that it had "no credible reports" that Turkish-backed mercenaries fighting in Libya had previously been involved with such terror groups.

Read more: Turkey criticizes Germany on enforcing Libya arms embargo

Follow the money

Instead, the Pentagon report pointed toward financial gain as the primary motivator for the mercenaries. 

"The mercenaries are 'very likely' fighting in Libya for personal and financial reasons rather than ideological or political motivations," said the report, citing intelligence gathered by USAFRICOM, the US military's unified combatant command for Africa-based operations.

Kristian Brakel, a former UN expert who now heads the Istanbul chapter of the German Heinrich Böll Foundation, which is affiliated with the Green party, supported the US findings, saying: "With a potential to gain up to $2,000 per month, it makes sense that many Syrians leave."

Despite the myriad of purported motivators for Syrians to fight for Turkey, the manner of recruitment for some even bucked the trend toward opposition fighters and militants. Germany-based Syrian activist Khaled Rawas told DW that at times, mercenaries are even recruited from refugee camps in Turkey. 

"Recruitment takes place through an envoy of the office of the Turkish governor who goes to the Syrian refugee camp," said Rawas, citing sources on the ground. "These liaisons generally describe the job as guarding vital facilities, which leaves recruits surprised when they find themselves on the frontline." 

Read more: 'Erdogan misusing refugees': Syrians in Germany on the Greek-Turkish border crisis