Russian and Syrian jets stepped up their bombing of an Islamic State bastion along the Jordan-Israel border in southwestern Syria, as the militants pushed into areas abandoned by other rebel groups, diplomatic and opposition sources said.
Islamic State-affiliated forces entrenched in the Yarmouk Basin, which borders the Israeli-occupied Golan Heights and Jordan, also repelled a ground attack by the Syrian army and its allies, the sources added.
The rural area has become the main battleground in the sensitive border region after a major Syrian army offensive backed by its Russian allies routed other rebel groups who were once supported by Washington, Jordan and Gulf states.