Turkish President Recep Tayyip Erdogan traveled to Russia today to negotiate the future of northern Syria — highlighting in the process the success of his audacious offensive, Vladimir Putin’s unmatched power in Syria, and America's absence from the table.Why it matters: American influence in Syria is evaporating in real time as U.S. troops withdraw. It's now Turkey and Russia that are effectively re-defining the country's borders and debating the fate of America's Kurdish allies.The deal announced today from Putin’s retreat in Sochi expands on the ceasefire Vice President Pence announced last Thursday, which was set to expire today, and covers three times as much territory.It would grant Erdogan the “buffer zone” he’s long demanded, running 20 miles out from the Turkish-Syrian border. Erdogan hopes to resettle Syrian refugees there, in apparent violation of international law.The deal gives Kurdish fighters an additional 150 hours to leave the zone, and their weapons, after which Turkey and Russia will conduct joint patrols along the border. Between the lines: Russia and the U.S. are both capitalizing on the U.S. exit from Syria. Putin will take pleasure in the fact that today's deal was reached without the U.S., but with its NATO ally.The deal could complicate Syrian dictator Bashar al-Assad’s efforts to regain control over all of Syria.Russia’s backing kept Assad in power through a brutal eight year civil war, but Erdogan was aiding the rebels seeking to topple him. Assad referred to Erdogan as a “thief” today in remarks carried on state TV.The other side: Kurdish forces held the territory until their superpower ally, the U.S., suddenly withdrew.A U.S. military convoy withdrawing from Syria for Iraq yesterday was pelted sporadically with fruit and stones by Kurdish civilians accusing the U.S of betrayal. “We never agreed to protect the Kurds for the rest of their lives,” President Trump responded back in Washington.Trump said the U.S. would keep small detachments in Syria at the request of Israel and Jordan and to “protect the oil," but there was otherwise "no reason" to remain.The bottom line: Trump has suggested that Syria is now Russia and Turkey’s mess to sort out. In this instance, they were happy to do so without him.Go deeper: Trump's Syria strategy — Get out, but "keep the oil"