Will this hasten the withdrawal from Syria, or reverse it? A suicide bomber struck a coalition patrol in Manbij this morning, killing multiple American troops. Shortly afterward, ISIS claimed credit for the attack and described in some detail how it was carried out:

ISIS has claimed responsibility for a deadly explosion that killed US service members in the Syrian city of Manbij on Wednesday. US service members were killed in the attack, according to a tweet from the spokesperson for the US-led coalition Operation Inherent Resolve. “U.S. service members were killed during an explosion while conducting a routine patrol in Syria today. We are still gathering information and will share additional details at a later time,” the tweet said. … The ISIS-affiliated Amaq agency said the attack in the northern city of Manbij was carried out by a suicide bomber with an explosive vest.

The US has not announced an official casualty count, but the Washington Post hears that four American soldiers died in the attack:

U.S. officials told The Post that initial reports suggested four Americans may have died. Earlier, Reuters news agency quoted an unidentified “U.S. official” as saying four American soldiers were killed and three wounded in the blast. There was no immediate confirmation of those figures from Operation Inherent Resolve, the U.S.-led coalition against the Islamic State. Statements published by the Islamic State’s unofficial news agency, Amaq, said the attacker used an explosives-laden vest to target coalition forces and that nine American troops were killed or injured. Amaq presented no evidence for that claim.

The overall casualty count thus far — unofficially — is 19, with ten killed. The success of the attack makes this tweet from a month ago look a little … premature:

We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency. — Donald J. Trump (@realDonaldTrump) December 19, 2018

At the time, critics warned that this could be Trump’s “mission accomplished” moment, and here we are. We certainly have done a lot of damage to ISIS and kicked it out of its most prominent redoubts, but we have not defeated ISIS in Syria. Its leadership remains at large and it still holds a handful of towns and villages in eastern Syria. The terrorist network retains enough operational capability to directly challenge American troops in the region, let alone conduct terror attacks abroad. Estimates of its strength range from 2,000 to 30,000, but even at the low end it’s enough of a core on which to rebuild once the US and others remove pressure from ISIS. That growth might take place in Iraq as well as Syria, as Sunni tribal chiefs chafe at the Shi’ite militias that are slowly spreading in their territories.

The White House announced that Trump has been “fully briefed” on the Manbij attack, as one would assume. Trump did state after his initial declaration of victory and withdrawal that he would not pull out until he was certain that ISIS would be destroyed. He could argue after this attack that it demonstrates the need to pull out rather than risk more American lives on a victorious outcome that is already cast in stone whether we remain or not. That would sound a lot like Barack Obama’s argument for pulling out of Iraq in 2011, a decision which allowed the former al-Qaeda in Iraq (AQI) to re-emerge as a marauding army in ISIS. That’s not a great precedent to follow, especially for a president who ran on the argument of Obama’s bad judgment in military matters.