Islamist rebels have captured a major airbase from Syrian government forces in the country’s northwest. Reports say the rebels expelled all Syrian forces from the Aby Duhur military airport in Idlib province.

The Britain-based Syrian Observatory for Human Rights says the al-Qaida-linked Nusra Front and allied Islamist groups are now in control of the airport. Syrian state TV confirmed that Syrian forces have left the area.

In related news, Russia has confirmed that members of its armed forces are present in Syria. A Foreign Ministry official said Wednesday that “Russian military experts” are in Syria to help its military become skilled in the use of Russian weaponry and other equipment.

A U.S. State Department official said Wednesday that Secretary of State Kerry spoke to Russian Foreign Minister Sergei Lavrov. Mr. Kerry reportedly expressed concern over the reports of Russian military involvement in Syria. He said that, if they were true, it could “leader to greater violence” in the country.