Video has emerged allegedly showing Russia's most advanced combat warplane in Syrian skies.

A Twitter user claimed the sighting of two Russian fifth generation Su-57 stealth fighters, nearby Russia's Khmeimim Air Base in southeastern Syria. Several air defense and support fighters provided escort. Russian and Syrian officials have yet to comment on the unverified footage. The new aircraft made its maiden flight last December. Earlier this month, a senior Russian defense official said many test flights must be carried out. The type was developed to match the US counterpart F-22 Raptor jets, which have been deployed to Syria.