STUTTGART, Germany — Turkey allowed the U.S. to resume air operations against the Islamic State from Incirlik Air Base after the Turkish base commander was detained in connection with this weekend’s coup attempt.

Turkey had closed the airspace around Incirlik on Saturday as the government said it had gotten the upper hand over a group within the Turkish military that had attempted a coup on Friday night. Throughout Saturday and Sunday, Turkish authorities were rounding up members of the military and justice system suspected of involvement in the failed coup attempt.

“After close coordination with our Turkish allies, they have reopened their airspace to military aircraft,” Pentagon spokesman Peter Cook said Sunday. “As a result, counter-ISIL coalition air operations at all air bases in Turkey have resumed,” he said, using an acronym for the Islamic State group.

The agreement with Turkey came on the same day that authorities took into custody the top Turkish general in charge and 10 other troops for their alleged role in the coup attempt. Incirlik Air Base not only plays a key role in the U.S. campaign against the Islamic State group but also houses U.S. nuclear weapons.

The first military flights resumed Sunday at about 2:30 p.m., several hours after Turkey authorized the reopening of the airspace, defense officials said.

U.S. facilities at Incirlik were still operating on internal power sources Sunday afternoon, but Cook said the hope was that commercial power would soon be restored. “Base operations have not been affected,” Cook said.

On Saturday at about 7:30 a.m., Turkish authorities cut off commercial power to the base, which it owns and operates.

The airspace was closed by 10:30 a.m. Saturday. Some officials said the move was intended to ensure that no Turkish air assets loyal to the rebels were able to operate from the base. But the sudden closure of airspace sparked fears among some analysts that the move was intended to pressure the U.S.

Turkish President Recep Tayyip Erdogan on Saturday asked the U.S. to extradite Turkish cleric Fethullah Gulen, whom Erdogan describes as the mastermind behind the failed overthrow. Gulen, who lives in exile in the U.S. and is an advocate for democracy and interfaith dialogue, denied any involvement.

Secretary of State John Kerry said the U.S. would review any request that included “legitimate evidence.”

Turkish Prime Minister Binali Yildirim said on Saturday that any nation supporting Gulen would be regarded as an “enemy” of Turkey.

Kerry in a call with Turkish Foreign Minister Mevlut Cavusoglu, cautioned that “insinuations” of American complicity in the attempted coup would have damaging political ramifications.

“He made clear that the United States would be willing to provide assistance to Turkish authorities conducting this investigation, but that public insinuations or claims about any role by the United States in the failed coup attempt are utterly false and harmful to our bilateral relations,” State Department spokesman John Kirby said in a statement.

The dispute over Gulen threatens to further rock an already troubled relationship between Washington and Ankara, and potentially puts operations at Incirlik in the political balance.

U.S. fighters, drones and refueling aircraft flying out of Incirlik have played a crucial role in the battle against the Islamic State group.

Since August, A-10 Warthogs and other aircraft have been a constant presence at Incirlik, expanding the U.S. coalition’s reach into Iraq and Syria. Prior to being able to fly out of Incirlik, the U.S. had relied solely on bases in the Middle East and carriers in the Persian Gulf to conduct operations.

Turkey had initially rejected U.S. requests to conduct operations from Incirlik when the campaign against the Islamic State began in 2014. But in summer 2015, Ankara reversed course. For pilots, that meant shorter flights to targets in Islamic State strongholds in northern Syria, where A-10s have played a prominent role .

During a December visit to Incirlik, Defense Secretary Ash Carter called the airmen leading the effort out of Incirlik the “tip of the spear.”

“You are first and foremost, and I’ll come back to this, hastening the defeat of ISIL, which has to occur and will occur, and this is a very important location in the point of the spear in that campaign,” Carter said.

With shorter flight times and air-refueling capabilities at Incirlik, pilots have been able to spend more time in the air, giving commanders a clearer picture of conditions on the ground. Flights out of Incirlik are responsible for an estimated one-third of all air refueling operations.

Given Incirlik’s status in the fight, a long-term loss of access to the base could require a reorganization of how assets are allocated and used in the campaign against the Islamic State.

The U.S. also has a small presence in Diyarbakir, a staging site for an Air Force search and rescue mission in southern Turkey. The U.S. and Turkey also have plans to position an American High Mobility Artillery Rocket System in southern Turkey to assist operations in Syria.

U.S. Central Command downplayed the effect of the halt on flights out of Incirlik on operations overall.

“While Incirlik (Air Base) provides a convenient location, it is important to remember that coalition aircraft operate from multiple other locations throughout Southwest Asia in support of counter-ISIL air operations, to include from U.S. naval assets in the region,” CENTCOM said in a statement.

For the U.S., the relationship with NATO ally Turkey has been fraught with complications. On the one hand, U.S. officials describe Turkey as a “stalwart” ally. On the other, Erdogan is viewed as a leader who over the past several years has demonstrated increasing authoritarian tendencies as he consolidates control in the country.

The U.S. also has called out Turkey for not doing enough to secure its borders, where militants have flowed back and forth to Syria. U.S support for Kurdish forces also has added to the tension between Washington and Ankara, which considers some Kurdish elements as the primary threat to Turkey.

Stars and Stripes reporter Chris Church contributed to this report.

vandiver.john@stripes.com