WASHINGTON — As the clock wound down on Barack Obama’s presidency, an Air Force B-52 bomber carried out a punishing airstrike against a training camp of Al Qaeda in Syria, the Pentagon said Friday.

The attack, which took place west of Aleppo, killed more than 100 fighters, according to the Pentagon. Armed drones were also involved in the operation, which took place Thursday evening local time.

It was the second major strike carried out by American warplanes in Mr. Obama’s waning hours in the White House. On Thursday, the Pentagon reported that B-2 stealth bombers had flown their first combat mission in nearly six years to attack two training camps in Libya that were being used by the Islamic State, which is also known as ISIS or ISIL.

The flurry of airstrikes against militant groups in North Africa and the Middle East illustrates the challenges that President Trump faces in carrying out the vow in his inaugural address to combat “radical Islamic terrorism,” which he promised to “eradicate completely from the face of the earth.” The extremists have proved to be resilient and are operating in far-flung countries that are racked by internal fighting and where there is little or no American military presence.