"Accidentally"
Aka "I believe in conspiracy theories rather than that accidents and friendly fire happen in warfare, especially when both sides are basically un-uniformed militias that are near impossible to tell apart"
1. Who invited the US led Coalition to bomb anyone in Syrian territory?, as far as I know, nobody. At the end of the day, this war will be remebered by how the US bombs illegally in a country without any permisson while the Russians are doing it legally, requested by the Syrian Govt.
2. It was not the first time the US-led Coalition bombed SAA positions around DeZ "by mistake". I'm not saying that the US directly aids ISIS in combat or with logistics, but their attitude is mysterious at best, same thing with the Turks, looking away when ISIS was right at their borders but now suddenly "they care".
3. Why does the US bomb Syrian Army formations moving whitin their own territory if there is no declared war?, who is the US to set up multiple Military Bases inside Syria and bomb anyone who gets near them?. They even shot down a Syrian jet not long ago, who was working on ISIS militants, but the US surely sees that Jet as a threat to their own existence and takes it down, because they fucking can. Now, what would happen if from all of sudden, a F/A-18 is shot down by the Syrian Air Defenses?, how many Tomahawks on Damascus are we talking about?. Lol, the US sees the SAA as an enemy everywhere but in DeZ, strange.
You know, it kinda reminds me of Israel bombing exclusively the Syrians while largely ignoring (and even assisting in some cases) known Yihadist groups near the Golan Heights. The US still sees Assad as their enemy, my ass they don't want to bring him down. Now they can't, mainly because Assad is stronger than ever, he has the upper hand and he has Russian and Iranian support. They lost.