According to the Pentagon, the attacks on Syrian government-backed forces were "defensive" because the Syrian fighters were approaching a US self-declared "de-confliction" zone inside Syria. The Syrian forces were pursuing ISIS in the area, but the US attacked anyway.
The US is training yet another rebel group fighting from that base, located near the border of Iraq at al-Tanf, and it claims that Syrian government forces pose a threat to the US military presence there. But the Pentagon has forgotten one thing: it has no authority to be in Syria in the first place! Neither the US Congress nor the UN Security Council has authorized a US military presence inside Syria.
So what gives the Trump Administration the right to set up military bases on foreign soil without the permission of that government? Why are we violating the sovereignty of Syria and attacking its military as they are fighting ISIS? Why does Washington claim that its primary mission in Syria is to defeat ISIS while taking military actions that benefit ISIS?