New footage to surface on social media late Wednesday night appears to show Russia’s most advanced fighter platform, the Su-57, arriving in Syria for combat operations.

The Su-57, also known as the PAK FA and T-50, is Russia’s most advanced fighter platform, widely believed to be a 5th generation competitor for the likes of America’s F-22, and China’s J-20. However, unlike the F-22, which entered service more than a decade ago, and the J-20, which reportedly became combat operational last week, the Su-57 remains years away from mass production and combat operations. To date, the Russian military has taken delivery on fewer than 12 of the prototype aircraft, which have already suffered repeated setbacks due to hardware issues and budget limitations.

So what is the untested platform doing in Syria?

It seems unlikely that the Su-57 was deployed to the Syria to meet a legitimate operational need. Russian President Vladimir Putin announced total victory over the Islamic State in December, when he also announced a planned withdrawal of Russian forces from Syria. However, in the time since, tensions have continued to escalate between the U.S. backed Syrian Democratic Forces and Bashar Al Assad’s sitting Syrian regime, which has received direct military support from the Kremlin.

Earlier this month, what some have called a proxy war between the United States and Russia over the future leadership of the Syrians state appeared to devolve into the traditional kind, with dozens or even hundreds of Russians being killed or wounded in a skirmish with U.S. Special Operations advisors co-located with SDF fighters on the American controlled side of the Euphrates River, which both sides recognize as the military deconfliction line. Russia has reluctantly acknowledged that there were Russian citizens among the dead a following that ill fated attack, but claims they were civilians serving alongside Syrian fighters on their own accord, rather than members of the Russian military. Russia, it’s worth noting, made similar claims about Russian soldiers fighting inside Crimea leading up to Russia’s military annexation of the region.