Militants advanced on a regime airbase in eastern Syria Thursday after the fall of a northern military airport, as Russia defended its military aid to embattled President Bashar Assad. The regime's most powerful ally dismissed criticism of its intervention from Western states, which are carrying out airstrikes on militants in both Syria and neighboring Iraq, though they also seek Assad's ouster. "We helped, are continuing to help and will help the Syrian government when it comes to supplying the Syrian army with everything it needs," Russian Foreign Minister Sergey Lavrov said. ISIS militants edged closer to a strategic air base outside the eastern city of Deir al-Zor in heavy clashes that left 54 fighters dead, said the Syrian Observatory for Human Rights. It said the extremist group, which has captured territory across Iraq and Syria, seized control of an army post near the base Wednesday night. Observatory director Rami Abdel-Rahman said 36 ISIS fighters and 18 regime soldiers were killed. ISIS fought its way to barely 1 kilometer from the airport with the seizure of the army post used by a rocket battalion. Two suicide bombers were used by the militants in the assault, one of them a child, driving cars laden with explosives, Abdel-Rahman said. ISIS already controls most of oil-rich Deir al-Zor province including about half of its capital, and has fought for over a year to capture the airport and the rest of the city. Deir al-Zor would be the second provincial capital to fall to the group after the northern city of Raqqa, which it has named the capital of its self-declared "caliphate." The Deir al-Zor assault came as rival militants from Al-Qaeda's Syrian affiliate and their allies Wednesday seized the last regime-held military base in the northwestern province of Idlib. According to the Observatory, the regime is now left with just three airbases in the east and north of the country – Deir al-Zor, and Neirab and Kweiris in Aleppo province – although it has military airports in other parts of Syria. At least 56 soldiers were killed, some execution-style, as rebels captured Idlib's Abu Duhur military airport under the cover of an intense sandstorm following a two-year battle, the Observatory said. Abdel-Rahman, whose Britain-based group relies on a network of sources on the ground in Syria, said at least 40 soldiers were taken prisoner and dozens more were missing. Rebels tweeted images of helicopters and planes abandoned on the tarmac. Abdel-Rahman said the entire province of Idlib was now under the control of the Nusra Front and other rebel groups. Assad's regime appeared to admit the loss, with state television saying troops had left the base. It has been at war with different rebel groups for the past four and a half years, in a conflict that has killed at least 240,000 people and forced millions more to flee abroad. A coalition led by the U.S. Wednesday bombarded ISIS militants Wednesday with 10 airstrikes in Syria and 18 in Iraq, a statement said. Russia Thursday denied it was ramping up its military presence in Syria, saying it was supplying its ally with humanitarian aid and military equipment under existing contracts and that its servicemen, including military experts, have been present inside Syria for many years. Russian officials have not commented directly on reports that Russian troops have taken part in combat. "Russian planes are sending to Syria both military equipment in accordance with current contracts and humanitarian aid," Lavrov told reporters in Moscow. "We have never made our military presence [in Syria] a secret," he said. "Russia is not taking any additional steps." U.S. officials said this week that Russia was solidifying its foothold in Syria, sending ships, armored personnel carriers and naval infantry. Lavrov rubbished suggestions that Russia's greater involvement in Syria would throw a wrench in the plans of the Western coalition's fight against ISIS militants. "This logic is incomprehensible to me," Russia's top diplomat said. "The Syrian army is the most effective force that can stand up to the terror threat on the ground."
