Story highlights One official told CNN that over recent months "we tried to take several shots at him"

The working assumption by the US is that Baghdadi remains alive

(CNN) The hunt for ISIS leader Abu Bakr al-Baghdadi is very much on.

CNN has learned that at one point over the summer the US believed they had their best shot at killing the terrorist leader in an airstrike, according to several US officials.

The strike, which has never been publicly disclosed, was based on intelligence that indicated a senior ISIS leader, quite possibly Baghdadi, was at the particular location. The officials familiar with the strike tell CNN it has never been definitively determined if Baghdadi was actually killed. But one official told CNN that over recent months "we tried to take several shots at him."

One reason the US remains uncertain if it killed Baghdadi is that in the days and weeks that followed the strike, US intelligence did not intercept any ISIS communications confirming his death and there was no discussion on ISIS social media accounts, US officials said. Given Baghdadi's stature, the US expects to see significant chatter discussing his death, if he is killed.

The strike occurred after a claim by Russia in June that the ISIS leader might have been killed in one of its airstrikes on the outskirts of Raqqa on May 28. The US has long believed that the Russian claim is not true.

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