A video purports just that albeit we can't vouch for it at this time. -- UPDATE: The video is now confirmed. The surroundings match the surroundings in videos of other Russian planes landing in Latakia.

Exclusive#Russia deploying its brand new fifth generation fighter jet the Su-57 in #Khmemeim AB #Syria



2 Su-57

4 Su-35

4 Su-25

1 A-50U were deployed in the #RuAF AB in Latakia/Jableh today pic.twitter.com/MA4NIKyMW7 — Wael Al Hussaini (@WaelAlHussaini) February 21, 2018

US 5th generation F-22s regularly confront Russian 4++ generation Su-35s over eastern Syria. Now Russia may be adding its own 5th generation technology into the mix.

This move comes a week after we've learned the US strike on Syrian army in Deir Ezzor earlier this month also killed 5 Russian private military contractors (actually technically three of them were East Ukranians).

The A-50 plane Russia sent is an AWACS plane, and perhaps an even more meaningful boost to Russia's air capabilities in Syria as it is only the second such plane Russia has in theater. (Now it can keep one airborne around the clock).

Anyhow it seems Syria will be Su-57s first war. A pair will be tested in skies over Syria.

USAF equips its F-22s that it flies over Syria with radar reflectors that make them highly visible to radar but also preclude Russians from learning too much about their true radar signature. Likely Russia will do the same with their stealth fighters.