Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan announced an agreement on Tuesday to clear Kurdish YPG forces 30 kilometers (18.6 miles) from the Syrian-Turkish border in order to establish a "safe zone" where Syrian refugees can be resettled.

Why it matters: American influence on the future of Syria is evaporating in real time as U.S. troops withdraw from the country. It's now Turkey and Russia that are attempting to redefine the country's borders and determine the fate of America's Kurdish allies.

The big picture: Turkey launched a military offensive into northern Syria on Oct. 9 after President Trump withdrew U.S. troops from the area. Erdogan has long sought to establish a buffer zone on the Turkish border in order to eliminate the threat from the Syrian YPG, which allied with the U.S. in the fight against ISIS but is considered by Erdogan to be an extension of the PKK — a Turkish separatist organization.

As a result of the Turkish incursion, Kurdish forces turned to Syrian dictator Bashar al-Assad, who is backed by Russia, for protection.

Vice President Mike Pence struck a deal with Erdogan last week to pause Turkey's offensive in northern Syria for 120 hours (five days) so that Kurdish forces can withdraw from the area. That "ceasefire" expires on Tuesday at 3pm ET.

As part of the agreement between Putin and Erdogan, YPG forces will withdraw 30 kilometers into Syria within 150 hours.

After that, Turkey and Russia will jointly patrol the area, help facilitate the return of Syrian refugees, and "continue to work to find a lasting political solution to the Syrian conflict," per the text of the agreement.

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