ISTANBUL — Russian bombers flying from an Iranian air base struck rebel targets across Syria on Tuesday, Russian and Iranian officials said, dramatically underscoring the two countries’ growing military ties and highlighting Russia's ambitions for greater influence in a turbulent Middle East.The long-range bombers took off from Hamadan in western Iran and launched raids in Syria's Aleppo, Deir al-Zour and Idlib provinces, the Russian Defense Ministry said in a statement Tuesday.