TRIPOLI, Libya — Islamic State militants unleashed suicide bombings Friday in eastern Libya, killing at least 40 people in what the group said was retaliation for Egyptian airstrikes against the extremists’ aggressive new branch in North Africa.

The bombings in the town of Qubba, which is controlled by Libya’s internationally recognized government, solidified concerns the extremist group has spread beyond the battlefields of Iraq and Syria and established a foothold less than 500 miles from the southern tip of Italy.

The militants have taken over at least two Libyan coastal cities on the Mediterranean – Sirte and Darna, which is about 19 miles from Qubba.