The base, which is located in the village of Ayn Issa, was previously used by the US-backed Syrian Democratic Forces (SDF).
Known as Syria's largest pro-government militia network, the National Defense Forces have repeatedly signaled readiness to continue their struggle against the Syrian Democratic Forces and US servicemen stationed in Syria, in a bid to prod then to withdraw from the Arab country.
Earlier this month, the Russian Defense Ministry said that the humanitarian situation in the city of Raqqa remains complicated as up to 30 civilians die due to mines every week.
Raqqa had been under the control of Daesh* militants since 2013; the city was declared their self-proclaimed capital" a year later.
In October 2017, Kurdish-led SDF troops, backed by the US-led coalition, announced the full liberation of the city after a months-long operation, something that was later confirmed by the Pentagon.
The US-led coalition has been launching air strikes on Syrian soil since 2014, in an anti-Daesh mission that was approved neither by the Syrian government nor the UN. Right now, an estimated 2,000 US troops are deployed in this Arab country.