Stop us if this sounds familiar. The US declares victory and goes home after a massive victory against an insurgency, only to see it metastasize in the vacuum left by our departure. That’s how we got ISIS in the first place after Barack Obama’s pullout from Iraq in 2011, and according to a new Pentagon report, that’s how we’re getting them again:

ISIS is “re-surging” in Syria less than five months after President Donald Trump declared the terror group’s caliphate there had been 100% defeated, according to a new Pentagon inspector general’s report on the fight against ISIS.

“Despite losing its territorial ‘caliphate,’ the Islamic State in Iraq and Syria (ISIS) solidified its insurgent capabilities in Iraq and was re-surging in Syria,” the report, which was published on Tuesday, warned. …

The report, from the lead inspector general for Operation Inherent Resolve, the official name for the US-led operation fighting ISIS, covers the period April 1 to June 30, 2019.

“The reduction of US forces has decreased the support available for Syrian partner forces at a time when their forces need more training and equipping to respond to the ISIS resurgence,” Glenn Fine, the principal deputy inspector general, wrote in a message accompanying the report.

There’s not much to say other than we told you so. (Or even more accurately, James Mattis told Trump so.) Driving ISIS into the desert wasn’t going to be enough to fully defeat it; as long as its leadership caste remained relatively intact, its reconstitution in one malevolent form or another was practically guaranteed. The IG report observes what was easily predictable last autumn — a lack of personnel on the ground meant less intel, less influence, and a shorter reach against potential areas of expansion.

The smaller footprint is also enabling Turkey to threaten our allies against ISIS. The Syrian Kurds who did most of the heavy lifting have to deal with a potential attack from the Recep Tayyip Erdogan regime, which is distracting them from the fight against the re-surging rump of the ISIS caliphate. The US is attempting to negotiate a “safe zone” in Syria as a buffer between Turkey and the Syrian Kurds, but that “safe zone” will likely get exploited by ISIS if and when it gets established:

Turkey’s defense minister says his country would like to establish a so-called “safe zone” in northeast Syria jointly with the United States but will act alone if necessary. …

He said the talks were progressing in a “positive” manner, adding that the American officials’ views were “moving closer” to Turkey’s.

Ankara wants to control — in coordination with the U.S. — a 19-25 mile-deep zone east of the Euphrates River in Syria, and wants no Syrian Kurdish forces there. Turkey sees the Syrian Kurdish fighters as terrorists aligned with a Kurdish insurgency within Turkey.

If US forces had remained in the region with the Syrian Kurds, Turkey would have thought better of making these kinds of threats — and the US could have secured a buffer zone between the YPG and Turkey. We would at least be in a much stronger bargaining position to keep Turkey away from the Kurds fighting ISIS. Instead, we have little leverage, especially since Trump has made it clear he has no interest in going back, and we’re basically attempting to create a safe zone for ISIS to attack Erdogan’s Kurdish enemies. And we wonder why we have such a tough time getting allies to work with us in this region.

It’s not for nothing that Lindsay Graham warned that Trump was making an “Obama-like mistake” in withdrawing at that time. That’s precisely what it was, and we’re getting the Obama-like consequences of making the same mistake all over again. If we fight a war, we have to fight it to win — and winning means destroying the enemy and especially its leadership or forcing them into surrender, rather than running out on our allies.