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A long-“frozen” conflict flared back to life this week. Dozens have been reportedly killed amid ongoing clashes between Azerbaijani and Armenian forces in Nagorno-Karabakh, a mountainous enclave of ethnic Armenians encircled by Azerbaijani territory. The new round of fighting that began over the weekend marks the bloodiest moment since the 1990s, when the two fledgling former Soviet states warred over disputed regions until a Russian-brokered cease-fire in 1994.

Both countries have mobilized their armed forces and blame the other for provoking the violence and killing civilians. The situation has been made more complex by the intervention of Turkey, which, unlike previous flare-ups when it urged a cessation of hostilities, has staunchly backed Azerbaijan and is allegedly even engaging in the clashes. Armenian officials said a Turkish F-16 shot down an Armenian fighter jet, a charge Azerbaijani and Turkish officials rejected.

More curiously, both Turkey and Armenia allege that the other side is importing mercenaries to the front lines. The Guardian reported that a group of Syrian fighters from Idlib province, the lone rebel-held bastion where Turkey holds considerable sway, were recruited in recent weeks to work for a private Turkish security company operating in Azerbaijan. According to the outlet’s sources, as many as 20 such fighters may have been killed in fighting this week in the Caucasus.

Ankara denies these claims and has wheeled around on Armenia, accusing the government in Yerevan of busing in Kurdish militiamen from the outlawed Kurdistan Workers’ Party, or PKK, to help train Armenian fighters in Nagorno-Karabakh. Whatever the veracity of these charges — and there are reasons to doubt them — they speak of a region riven with ethnic grievances and deep-seated political enmities.

They also point to a broader emerging phenomenon of mercenary outfits on the front lines of the 21st century’s wars. Turkey, after all, established a template for enlisting Syrian fighters for its proxy wars when it transported hundreds to Libya to aid the government in Tripoli. Its apparent involvement in Azerbaijan adds to the conspicuous set of geopolitical confrontations initiated by Turkish President Recep Tayyip Erdogan, including entering the Libyan civil war; enabling the rebels’ last stand in northwestern Syria; engaging in a tense maritime dispute in the eastern Mediterranean that’s pulled in France and other European governments; and waging its long-running battles with Kurdish separatists operating along the borders of Syria and Iraq.

“Most of the Syrian fighters in Libya have been hired by Turkey, which sponsors militias inside Syria opposed to the government of Syrian President Bashar al-Assad,” my colleagues Kareem Fahim and Zakaria Zakaria reported earlier this year. “Turkey also is the main military supporter of Libya’s U.N.-recognized government, known as the Government of National Accord, or GNA.”

But Ankara is hardly alone on this front. The Wagner Group, a Kremlin-linked Russian private security company, has deployed mercenaries over a wide spectrum of the world’s battlefields, from eastern Ukraine to Syria and Libya. And, often with the financial support of the United Arab Emirates, Sudanese fighters have served as ground troops in civil wars in Yemen and Libya.

My colleagues reported that hundreds of Syrians aligned with the Assad regime and its Russian backers were also hired to support the rogue Libyan commander Khalifa Hifter, whose offensive against the GNA was successfully repelled with Turkish aid earlier this summer. A U.N. report this month tracked some 338 Russian military cargo flights from Syria to Libya in support of Wagner, operating on Hifter’s behalf. The report said Russia, the United Arab Emirates, Qatar, Turkey and Jordan were all violating a U.N. arms embargo on Libya by ferrying military equipment and supplies to the dueling sides in the conflict.

Ordinary Syrians have become pawns in this regional conflagration. “At a time when the Syrian economy and currency are collapsing, it is difficult for prospective fighters to pass up the generous financial packages offered for heading to Libya, offers that include salaries of $2,000 a month, a $500 advance for families left behind in Syria, and the promise of several thousand dollars in death benefits,” my colleagues reported.

Half a decade ago, state collapse and economic hardship were seen as drivers for Islamist militants flocking to the chaos of the Syrian war. Now, some of these combatants are being funneled into new conflicts stirred by rival nation-states. The prevalence of Syrian fighters in places like Libya, argued Frederic Wehrey, a senior fellow at the Carnegie Endowment for International Peace, reflects “a global trend toward the outsourcing of extraterritorial military force driven partly by the availability of itinerant, pay-for-hire fighters from failed revolutions and civil wars in Africa and the Middle East and the growth of private military companies.”

These outfits may see this week’s battles over Nagorno-Karabakh as a new opportunity. Russian officials have urged a cease-fire and cooling of tensions, but experts fear things could escalate as Turkey upsets a delicate balance of power. Ankara and Moscow could find themselves confronting each other in a third proxy conflict if Azerbaijani-Armenian clashes stray beyond Nagorno-Karabakh.

“If we see this conflict spill over into other parts of the geography … that will trigger a much more difficult episode between Turkey and Russia which will come on top of the existing theatres of conflict in Syria and Libya,” Turkish analyst Sinan Ulgen told the Financial Times.

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