American troops hastily retreated from positions in northeastern Syria this week as Turkey pushed its operation against Kurdish-led militias there.
The bombing came just weeks after President Donald Trump declared victory over ISIS and ordered a withdrawal of U.S. forces from Syria.
"The caliphate has crumbled and ISIS has been defeated," the vice president said hours after the apparent suicide attack.
Turkish President Recep Tayyip Erdogan said, "Trump will not turn back due to this act of terrorism because I have seen his determination to withdraw."
Turkey and its insurgent allies are sweeping through Kurdish territory and risking an international conflict with the U.S., France, Syria and Iraq.
Once a primary recipient of CIA assistance, the Free Syrian Army has since turned on U.S. efforts to battle ISIS using Kurdish militias.
In a message to besieged ISIS fighters in former stronghold Manbij, a commander tells them not to come back alive.
As Kerry pleads with Russia to bring his military actions in Syria into line with their stated intentions, Putin senses craven weakness.
Thousands of items could hold key intelligence about foreign fighters and the group's inner workings.
ISIS also managed to repel government troops in Raqqa province.
Paris is providing weapons, air support and advice to French troops in the campaign to capture Manbij.