Transcript for 4 Americans among the dead in Syria attack

We have new details about the deadly suicide bombing in Syria. Four Americans including two U.S. Service members among at least 16 people killed. ISIS is claiming responsibility. Now, this is just weeks after president trump claimed ISIS was defeated and announced the U.S. Would withdraw all of its troops. Terry Moran has more at the white house for us. Good morning, Terry good morning good morning. The president heads to the Pentagon this morning to announce his new missile defense policy but so far he has made no statement on that deadly suicide attack in Syria. The deadliest attack on U.S. Troops since American forces went into that country in 2015. A busy downtown street in Syria. Suddenly a pfeiferball explosion in a local restaurant. A suicide bombing. Reporter: 16 people killed including four Americans. Among the dead we know two active duty service members, a civilian defense department employee and a contractor. As their families are notified and the military investigates, ISIS has claimed responsibility. Just weeks after president trump said this when ordering U.S. Troops out of Syria. We have won against ISIS. We've beaten them and we've beaten them badly. Reporter: The attack raised sharp questions about whether the president's sudden decision to pull out of Syria was premature. Some Republicans even suggesting trump's boasting might be spurring ISIS to kill Americans. My concern about the statements made by president trump is that you set in motion enthusiasm by the enemy we're fighting. Reporter: Hours after vice president pence repeated the president's claims. The caliphate has crumbled and ISIS has been defeated. The idea that ISIS or the caliphate has crumbled, that we have defeated ISIS smacks of a mission accomplished moment and really is naive at best, possibly delusional. Dangerously so. Reporter: American forces were meeting with locals in the strategically vital town of manbij when the blast occurred. Three other service members were injured. Since the president announced his withdrawal from Syria, the time line has changed. He said the troops were coming out soon. Now it's clearly going to take longer so that the withdrawal can be orderly, coordinated with allies and safe, George. Based on conditions on the ground. We're learning new details

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