US military officials have told The Wall Street Journal that Russia forces have carried out multiple military operations against the US-led coalition in Syria this month. This included a Wednesday attack on the al-Tanf garrison along the Iraq border in southeast Syria, though so far it appears the operations have targeted American proxies, namely local Arab and Kurdish factions that US trainers have been supporting.
Given that Russia informed the Americans of the attacks ahead of time via a military-to-military communications line, the Pentagon believes Russia "wasn’t actively targeting American troops but was harassing the US mission in Syria."
With al-Tanf, US officials described that "a combat outpost at the garrison" was hit in the Russian strike, but no US troops were there at the time, in an attack that appeared to target ”US-backed Maghawir al-Thawra fighters" - which Russia says was responsible for an earlier roadside bomb attack against its troops. There were no reports of casualties, as coalition forces quickly evacuated due to the prior Russian warning.
It's clear that this is perhaps the closest Russian and US forces have ever come to direct conflict, something the Pentagon has expressed a desire to avoid, but said Russia's recent actions are a serious "provocation" and mark an escalation.
"We seek to avoid miscalculation or a set of actions that could lead to unnecessary conflict: that remains our goal," Army Gen. Erik Kurilla, the head of US Central Command said. "However, Russia’s recent behavior has been provocative and escalatory."
CNN added in a follow-up to the WSJ report:
The initial US assessment is the Russian forces were likely ordered to notify the US ahead of time and conduct the airstrikes knowing they would not hit US troops and that the Americans would warn their allies, the officials said.
But the Russians still likely achieved their goal of "sending a message" to the US that they can strike without being worried about retaliation, one official said.
There have been a number of 'close calls' between US and Russian troops operating in Syria over the years. Russian forces are there at the invitation of the Syrian government, while President Assad has called the Americans hostile foreign occupiers and demanded they withdraw. Sometimes the rival convoys block each other in standoffs on key Syrian roadways near areas of the US occupation, which is heaviest in the northeast.
However, some observers are seeing in this month's strikes near US positions a deliberate signal that things are intensifying related to Ukraine, and the Kremlin is engaged in muscle-flexing in the face of the some 900 US troops still in Syria.