Three days after a chemical weapons attack killed dozens of civilians in Syria, the US reacted by launching its first direct military strikes against the Syrian regime. br The US launched 59 Tomahawk cruise missiles from its warships in the eastern Mediterranean early Friday, taking aim at the Syrian airbase it believes houses the aircraft that carried out the attack. br But it's not just Syria that uses the Shayrat airfield -- Russia, its key ally, has forces based there too. br br br Despite being warned of the attack in advance, it appears Russia did not deploy surface-to-air missiles, which are capable of taking out US Tomahawk missiles. br The base itself goes back a long way and has been home to a mix of aircraft including Soviet-era MiG 23, MiG 25 and Su 22 jets. br The base also has between 45 and 50 hardened hangars on site. br Russia has had forces deployed at Shayrat since late 2015 as part of its current operation in Syria, and has used Shayrat to launch attacks against ISIS in the battle for the city of Palmyra. br Russia uses it as a forward operating base for attack helicopters and has invested a lot of money in updating and upgrading the base, though it has now been severely damaged by the US military. br The Russians were given a "very brief notice" prior to the strike on the military base, a US defense official told CNN. br It is unclear if that notice enabled Russian or Syrian forces to evacuate personnel and equipment from the base. br Six people were killed in the strikes, according to Syria, but there are no reports of Russian casualties.