The U.S. has carried out airstrikes in Libya in order to help the fledgling government in Tripoli move against an Islamic State stronghold in the northern coastal town of Sirte, the Pentagon announced Monday.

A Pentagon statement says the airstrikes were conducted at the request of the new Libyan Government of National Accord and were authorized by President Obama acting on the recommendations of Defense Secretary Ash Carter and Joint Chiefs Chairman Gen. Joseph Dunford.

Forces aligned with the new government have already captured territory surrounding the city of Sirte, and the Pentagon said American airstrikes were designed to enable the Libyan government-backed forces "to make a decisive, strategic advance."

While the U.S. has conducted unilateral strikes aimed at individual Islamic State members, this is the first time the U.S. has provided air cover for Libyan fighters on the ground.

The strikes were described as consistent with the U.S. approach to combating the Islamic State by working with "capable and motivated local forces." The Pentagon said it plans more strikes in the coming days.

"The U.S. stands with the international community in supporting the GNA [Government of National Accord] as it strives to restore stability and security to Libya. These actions and those we have taken previously will help deny ISIL a safe haven in Libya from which it could attack the United States and our allies," the statement said.

At a Pentagon briefing, spokesman Peter Cook told reporters U.S. support would continue as long as the Western-backed unity government requested help, and said the goal is to dislodge the Islamic State from Sirte, which it seized last year.

"We don't have an end point at this particular moment in time," Cook said. "But we'll be working closely with the GNA and we certainly hope that this is something that does not require a lengthy amount of time."

Cook said the U.S. military would be coordinating closely with Libya over the target selection. "We will be reviewing and deciding those list of targets after, again, close consultation with the GNA," Cook said.

One of the targets hit Monday was a single tank that Cook said was blocking the advance of anti-Islamic State forces and firing indiscriminately on civilians. "It is that kind of precision location, precision target, that we'll be targeting that the GNA at this point felt like that would be a helpful support for their efforts," Cook said.