The US has been increasingly attacking pro-government forces in eastern Syria, but this is the first time that they've shot down a manned Syrian aircraft, and the fact that it happened within Syrian airspace is likely to dramatically add to the tensions between the two sides.
"At 6:43pm (17L43 GMT), a Syrian regime SU-22 dropped bombs near SDF (Syrian Democratic Forces) fighters south of Tabqa and, in accordance with rules of engagement and in collective self-defence of Coalition partnered forces, was immediately shot down by a US F/A-18E Super Hornet", the Combined Joint Task Force said in a statement.
Over the last four weeks, the USA has conducted three airstrikes at pro-regime Assad forces, backed by Iran, that have moved into a deconfliction zone around the town of at Tanf in southwest Syria, which is the location of a coalition training base for local forces fighting ISIS.
A statement distributed by the Syrian military and distributed on Twitter said that the aircraft's lone pilot was killed in the attack. As the attack unfolded, the USA military used a deconfliction channel to communicate with the Syrian government to stop the skirmish, according to the Pentagon statement.
By cutting off the Syrian Army from the road to Deir Ezzor, the US-backed forces will have access to several oil fields that are desperately wanted by the Syrian government.
Just hours earlier, the United States bombed Syrian government and allied troops inside a protected zone in that area, and marked a sharp escalation in the skirmishes between the coalition and pro-Syrian government forces there.