Su-22 Down
By 
So we got this going on:
A U.S. Navy F/A-18E Super Hornet from Carrier Air Wing 8 on board the USS George Bush shot down a Syrian Air Force Su-22 ground attack aircraft near Raqqa, Syria after the aircraft struck ground troops in Ja-Din, south of Tabqah, near Raqqa.
According to most sources it is the first time a U.S. combat aircraft has shot down a manned enemy aircraft in aerial combat in nine years.
The pro-Assad regime Syrian Su-22 that was downed had attacked Syrian Democratic Forces aligned with the U.S. led coalition and inflicted casualties on the friendly forces as they were driving south of Tabqah before it was intercepted.
Hopes that Trump would be anti-interventionist… may not be wholly rewarded. This is the latest of a series of quiet escalatory steps that the Trump administration has either undertaken or allowed to be undertaken in Syria; with the leeway that Trump has granted local commanders, the reasoning for these steps is unclear.
Russia is displeased.
BREAKING: Russia says it will treat US-led coalition planes in Syria, west of the Euphrates, as targets after US downed Syrian jet.
— The Associated Press (@AP) June 19, 2017
Ever since the US started bombing ISIS targets in Syria, the Assad government and the US military have been involved in an uneasy, low-key, but generally productive collaboration, at least insofar as the remnant Syrian air defense network would avoid targeting US aircraft, and vice versa. There isn’t much left of that network now, but in any case we can expect altogether less cooperation moving forward.