Reports out of Moscow confirm a Russian military transport aircraft crashed in Syria on Tuesday. All 26 passengers and six crew members are confirmed dead. Everyone on board was Russian military personnel.

The Antonov An-26 dual prop transport and cargo aircraft reportedly crashed as it was approaching a runway at Russia’s Khmeimim airbase in the Latakia province. The aircraft was making its approach, when it abruptly lost altitude and collided into the ground 1600 feet short of the runway. Initial indicators say that the failure may have been technical or pilot-based in nature, as there has been no evidence to suggest terror activity and the aircraft was not under fire during its approach.

According to the Russian Defense Ministry statement regarding the incident, an investigation into the cause of the crash is already underway, though no further details were available at this time.

This incident marks a significant uptick in the deaths of Russian troops the Kremlin has been willing to acknowledge since they began offering direct military support to Syrian President Bashar al Assad in 2015. According to official statements from the Russian government, about 46 Russians had been killed in Syria since then, prior to Tuesday’s incident, though most experts agree that Russian casualties have gone significantly underreported.

The aircraft that crashed, an Antonov An-26, has been out of production since 1986 and does not boast a particularly impressive safety record. According to the Aviation Security Network, which maintains a database of aviation accidents, Antonov An-26s have been involved in more than 140 incidents, claiming the lives of more than 1,300 people in all. However, some credit the aircraft’s ability to take off and land using undeveloped and rough field airstrips for an unfair depiction of the vehicle’s safety. Because these aircraft are so regularly operated in less than ideal environments, the chances for failure or mishap will always be higher.

Early last month, a Russian flagged Su-25 was shot down by Syrian rebels. The pilot ejected and survived his landing, only to later blow himself up with a grenade, according to Russian state-owned media outlets, to avoid capture. Last month, a direct engagement between Pro-Assad Syrian troops bolstered by a force of as many as hundreds of Russian mercenaries launched an offensive against an SDF outpost with U.S. Special Operations advisors on site.

The U.S. military launched a counter-offensive that obliterated the 500 strong advance. Russia first claimed that there were no Russians involved in the ill-fated attack, then later adjusted their story to claim the hundreds of Russian fighters killed in the incident were mercenaries with no affiliation with the Kremlin whatsoever — another claim that has been widely refuted.

A litany of diverse groups with backing from various nations outside the Syrian border, including the Syrian Democratic Forces backed by the United States, have been fighting an ongoing war against the Islamic State and one another for territory and leverage since 2011, with those squabbles occasionally even involving direct action between foreign nations in support. A Syrian Su-22 was shot down by a U.S. Navy F/A-18 Super Hornet last June, and an Israeli F-16 was shot down last month after responding to an Iranian drone that crossed over the border into their airspace.