The Pentagon said Tahliil Abdishakur's "death will significantly impact al Shabaab's ability to conduct attacks."
A spokesman of the militant group said it "targeted the enemies at a time they were celebrating Christmas."
At least 36 non-Muslim workers were killed, including two being beheaded
Gunmen ordered non-Muslims off a bus Saturday and shot 28 dead. Muslim passengers were spared.
The Somali Islamist militant group al Shabaab, which attacked the Westgate shopping mall in Nairobi last September, took credit