Cook said the strikes were approved by President Obama upon the recommendation of the chairman of the Joint Chiefs of Staff and the U.S. secretary of defense.
The strikes were carried out by both manned and unmanned aircraft, a Pentagon official said. At least one of the strikes hit a tank operated by ISIS fighters.
Almost all U.S. and coalition strikes against ISIS up to this point have been conducted inside Iraq and Syria. But ISIS is known to have a presence in Libya as well. These strikes, Cook said, will help Libyan government forces build on some of the success they have already had in recapturing territory from ISIS around Sirte.
Cook also signaled in his statement that these strikes represent the first of a broader campaign in Libya: “Additional U.S. strikes will continue to target ISIL in Sirte in order to enable the GNA to make a decisive, strategic advance." Cook said the pace and duration of this campaign will depend on what the Libyan government requests.