Russian President Vladimir Putin’s hand lurks very close in Wednesday’s attack by Assad regime forces on the Syrian Democratic Forces in a northern sector east of the Euphrates river.

Facing that attack, the SDF and embedded U.S. special operations personnel held their position with the support of U.S. air and artillery strikes. The regime’s forces suffered perhaps 100 dead and lamented American "aggression."

Still, I am 90 percent confident that the Russian defense ministry is lying in its claim that Syrian President Bashar Assad's forces acted without their prior forewarning and Russian support. For a start, as I argued last December and in January, Russia is likely to carry out an attack against U.S. forces in Syria. And this is that attack, or at least one of them.

While the SDF was the official target, this attack is ultimately rooted in a Russian effort to push the U.S. out of Syria. The Russians deeply oppose the U.S. effort — as orchestrated by Secretary of Defense Jim Mattis — to retain influence in Syria in order to help shape multi-sectarian political transition away from Assad — or at least to counterbalance the influence of Russia, Iran, Turkey, and Assad.

As an extension, Assad doesn’t do anything against the SDF or U.S. military which the Russians haven't first authorized or ordered. This is especially true in incidents such as Wednesday’s in which Assad’s forces advance past the deconfliction line. Assad and Russia would have known that those forces would come into contact with the U.S. military. As I say, that was the whole intent: they sought to test how the U.S. would respond and hopefully push the U.S. back.

Another indicator of Russia's hand came immediately following the attack when CNN’s Barbara Starr tweeted that Russian contractors might have been involved.

Here's the thing, Russian contractors actually translates as Russian intelligence special forces; in this case probably from the GRU. It's KGB Vladimir's way of serving his tactical interests while also protecting himself against accusations of direct involvement in any sensitive incident.

All that said, while this attack failed, it is a signal of a broader Russian strategy and of new incidents yet to come.

Putin will do what he always does and escalate until he is deterred. In that context, it is of credit to President Trump that he has clearly authorized the theater combatant commander to use reflexive force to defend the SDF and U.S. personnel from any attack.