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.
The B-52 strike on Thursday, the Pentagon said, was directed at the Shaykh Sulayman Training Camp in Idlib. Pentagon officials said that it had been in operation for several years but had only recently become a base for “core Al Qaeda” extremists, who have largely come from outside Syria to fight and plot attacks. All told, 14 bombs and missiles were used in that attack.
“The removal of this training camp disrupts training operations and discourages hard-line Islamist and Syrian opposition groups from joining or cooperating with Al Qaeda on the battlefield,” Capt. Jeff Davis, a Pentagon spokesman, said in a statement.
The airstrike was condemned by the Syrian opposition group Jabhat Fateh al-Sham, which complained that the camp for new recruits was one of theirs and that the practical effect would be to eliminate fighters who are confronting Bashar al-Assad, the Syrian leader. Jabhat Fateh al-Sham, formerly known as the Nusra Front, claims to have broken with Al Qaeda, but American officials say they are still a Qaeda affiliate.
“America chose to confront the Syrian people and their mujahedeen,” the group said in a statement, which was translated by the SITE Intelligence Group, which studies terrorist groups.
The Pentagon has announced other attacks against Qaeda operatives in recent days, asserting that more than 150 terrorists had been killed since Jan. 1.
On Thursday, the Pentagon disclosed that it had carried out an airstrike on Tuesday in Idlib Province that killed Mohammad Habib Boussadoun al-Tunisi, whom it described a Qaeda leader linked to plots against Western targets.
According to a Pentagon statement, Mr. Boussadoun went to Syria in 2014 after spending several years in Europe and other countries in the Middle East where he maintained ties with extremists. Earlier in January, airstrikes killed two other Qaeda leaders, the Pentagon said.