Three U.S. officials told CNN that there are now signs Abu Omar al-Shishani survived the strike, which the Pentagon said occurred in the environs of the town of al-Shaddadi, Syria.
One official told CNN definitively, "he's alive." A second official said "there is anecdotal evidence he is alive." And a third official said there is a "small" intelligence indicator he is alive but declined to disclose the intelligence.
At least one person was observed by aircraft to have left the scene following the strike.
In an initial assessment, a defense official told reporters Tuesday that Shishani "was likely killed," along with 12 additional ISIS fighters, in a wave of strikes by drones and manned aircraft.
Since then, CNN has learned that Shishani was at a "shura," or meeting with other officials, at the time of the strike. U.S. officials had emphasized at the time it was publicly announced that they were not certain of his death and were assessing whether the strike killed him.
One reason the U.S. initially thought Shishani had been killed is that intercepts of his communications had gone silent, CNN has learned.
But this situation was a bit unusual, coming together quicker than most. The strike was quickly called in, one official said, when there was sudden intelligence that Shishani was at the meeting. The aircraft and drones had already been patrolling in the skies.
It is not clear if there is a relationship between the quick call for a strike and the possibility that Shishani survived. There was also no explanation for why the aircraft were not able to continue to fly overhead to monitor the situation.
U.S. officials said Shishani had traveled to the al-Shaddadi area from ISIS' unofficial capital of Raqqa to meet with troops in the region who had been in heavy combat and suffered losses.
The Pentagon has offered different locations for precisely where the strike happened, in one instance saying it was near al-Shaddadi but in a press release indicating it happened near al-Hawl several miles away.
The officials also said the U.S. is monitoring social media for additional reports that Shishani may have survived.
The activist group Syrian Observatory for Human Rights reported Shishani was "critically injured" in the strike but survived and made it to Raqqa.