Trump's step back from the border turns into a sprint from Syria

President Trump stepped aside and Turkey's Recep Tayyip Erdogan marched forward. Over the ensuing week, a delicate balance in Syria has collapsed.

Why it matters: Alliances have been hastily redrawn, civilians have fled in panic, and the U.S. has announced a near-total withdrawal. In the balance are an increasingly fragile victory over ISIS, what's left of the U.S.-Turkey alliance, and the future of Syria and its Kurdish inhabitants.

Catch up quick...

• Turkey has advanced farther and more rapidly than the U.S. anticipated. Militias it supports have allegedly executed Kurdish civilians and, according to Foreign Policy, freed ISIS captives.
• Abandoned by their U.S. allies, Kurdish forces struck a deal with Syrian dictator Bashar al-Assad and his patron, Russia. Today, Syrian forces began flooding into Kurdish-held territory.
• President Trump today announced that nearly all U.S. troops in Syria will be moved elsewhere in the region. Defense Secretary Mark Esper had said they risked being trapped between advancing armies.

The big picture: “Trump’s acquiescence to Turkey’s move to send troops deep inside Syrian territory has in only one week’s time turned into a bloody carnage, forced the abandonment of a successful five-year-long American project to keep the peace on a volatile border, and given an unanticipated victory to four American adversaries: Russia, Iran, the Syrian government and the Islamic State,” the NYT’s David Sanger writes.

Behind the scenes: This was all born from a bluff, Axios' Jonathan Swan explained today on the Pro Rata podcast.

• Dating back to 2017, Swan reports, "Trump had been telling Erdogan: 'You wanna go in there? Ok, it’s all yours. You take care of ISIS, you take care of the whole thing. You own all of it.'"
• "Trump just kept running the same play again and again ... and this time Erdogan was like, 'fine, that's exactly what we'll do.'"
• “Part of the problem is, Trump really doesn't care about the Kurds. In his mind, he can put a big tick next to clearing out the ISIS caliphate and he just wants to get U.S. troops out, full stop."
• However, Swan reports, “He is starting to realize that the result of that phone call is a disaster on the ground.”

The latest: In a statement this evening, Trump said the U.S. forces leaving Syria will remain in the region to guard against an ISIS resurgence.

• He also announced a suspension of trade talks with Turkey, a hike in steel tariffs to 50%, and potential "powerful additional sanctions" against those guilty of "serious human rights abuses."

What to watch: Turkey wants to force Kurdish forces from its borders and resettle Syrian refugees in the new buffer zone. Assad wants to regain control over all of Syria. The Kurds want protection from Turkey and, if possible, a degree of autonomy.

• Russia, meanwhile, has relationships with all the key players and a military presence in Syria, says Rob Malley, CEO of International Crisis Group and a former Obama administration official.
• “This is now being played out in the worst possible circumstances. It appears to be a free-for-all, and it’s hard to see a party other than Russia at this point who could orchestrate a settlement."