(CNN) In President Barack Obama's last major military attack against al Qaeda, more than 100 members of the group were killed in a US airstrike in western Syria on Thursday, according to a defense official.

The strike -- which the Pentagon confirmed Friday afternoon in a statement -- hit a training camp west of Aleppo, near the Turkish border. A US B-52 bomber, along with armed drones, dropped 14 munitions on the camp, the official said. The site of the camp was well known to US intelligence.

"The Shaykh Sulayman Training Camp was operational since at least 2013," Pentagon spokesman Capt. Jeff Davis said in the statement. "The removal of this training camp disrupts training operations and discourages hardline Islamist and Syrian opposition groups from joining or cooperating with al-Qaida on the battlefield."

Davis noted that US strikes have killed 150 al Qaeda fighters since the start of the year.

"These strikes, conducted in quick succession, degrade al Qaeda's capabilities, weaken their resolve, and cause confusion in their ranks," he said.

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