Rosaviatsiya, the federal aviation administration for #Russia, has informed state airlines that pilots should exercise caution while operating over the Eastern Mediterranean in fears of possible US airstrikes on Syria.
https://lenta.ru/news/2018/04/10/rosavia/
Civil aviation warnings and NOTAMS does not mean an imminent attack, just a heads up and use alternate flight routes.
Russia know a lot about shooting down civilian air traffic...