Who's calling the shots in Syria - and who's not?

Those pesky Russians. They buzz our planes and ships. Their subs and spy ships aggressively hover around the areas where vital undersea cables that carry most of the world's Internet communications are located. They hold frequent back-and-forth state visits with top officials of Iran.
And now this:

The U.S. has stopped flying manned air-support missions for rebels in a key part of northern Syria due to Russia’s expansion of air defense systems there, and the Barack Obama administration is scrambling to figure out what to do about it.

Russia’s military operations inside Syria have been expanding in recent weeks, and the latest Russian deployments, made without any advance notice to the U.S., have disrupted the U.S.-led coalition's efforts to support Syrian rebel forces fighting against the Islamic State near the Turkey-Syria border, just west of the Euphrates River, several Obama administration and U.S. defense officials told us. This crucial part of the battlefield, known inside the military as Box 4, is where a number of groups have been fighting the Islamic State for control, until recently with overhead support from U.S. fighter jets. 

But earlier this month, Moscow deployed an SA-17 advanced air defense system near the area and began “painting” U.S. planes, targeting them with radar in what U.S. officials said was a direct and dangerous provocation. The Pentagon halted all manned flights, although U.S. drones are still flying in the area. Russia then began bombing the rebels the U.S. had been supporting. (U.S. manned airstrikes continue elsewhere in Syria.)

Inside the top levels of the administration, officials are debating what to do next. The issue is serious enough that Secretary of State John Kerry raised it with Russian President Vladimir Putin when they met on Tuesday, and Joint Chiefs of Staff Chairman General John Dunford has discussed it with his Russian counterpart as well, a spokesman for U.S. Air Force Central Command told us.

"The increasing number of Russian-supplied advanced air defense systems in Syria, including SA-17s, is another example that Russia and the regime seek to complicate the global counter-Daesh coalition’s air campaign,” said Major Tim Smith, using another term for the Islamic State.

The increasing number of Russian air defense systems further complicate an already difficult situation over the skies in Syria, and do nothing to advance the fight against the Islamic State, which has no air force, Smith said. He added that Russia could instead be using its influence with the regime to press President Bashar al-Assad to cease attacking civilians. “Unhelpful actions by Russia and the Syrian regime will not stop coalition counter-Daesh operations in Syria, nor will such actions push the coalition away from specific regions in Syria where Daesh is operating,” said Smith. 

Post-America: Russia's bitch.