This is not the first time American spy planes have conducted survey flights along Syria’s maritime borders, near Russia’s Hmeymim air base and Tartus naval base. US planes also regularly conduct recognisance close to Russia’s borders in Kaliningrad and around Crimea.
A US P-8A Poseidon plane, fitted to detect ships and submarines, has been detected flying along the Syrian coast by several aviation enthusiasts keeping an eye on flight radars on January 30. The plane made several passes along the Syrian maritime border flying at an altitude of 4.7km and then returned to its base in Sicily.
https://twitter.com/Intel_sky/status/1090572751205789697