Syrian Kurdish-led forces seized ISIS’ main hub of Hajin Friday, a milestone in a massive US-backed operation to eradicate the militants from their single remaining enclave in eastern Syria. The Syrian Democratic Forces secured Hajin, the largest stronghold in what is the last pocket of territory controlled by the terrorist group, the Syrian Observatory for Human Rights said. After a week of heavy fighting and air strikes by the US-led Coalition, “the SDF were able to kick ISIS out of Hajin," Rami Abdel Rahman, the head of the Britain-based monitor, said. The operation was completed at dawn, he said, a day after SDF forces fanned out across the large village in the Euphrates valley. On Thursday, the last ISIS militants were confined to a network of tunnels and the edges of Hajin, which lies in the eastern province of Deir Ezzor, about 30 kilometers from the border with Iraq. The area held by the extremist ogranization is sometimes referred to as the "Hajin pocket", the last rump of a once-sprawling "caliphate" ISIS proclaimed in 2014 over swathes of Syria and Iraq. Extremists pulled back to positions east of Hajin Friday and to Sousa and Al-Shaafa, the two other main villages in their shrinking Euphrates valley enclave. According to Abdel Rahman, a total of 17,000 fighters from the Kurdish-Arab SDF alliance are involved in the operation to flush ISIS out of its last bastion. The operation was launched on September 10.