Turkey has agreed to allow the U.S.-led coalition to use its military bases for the fight against the Islamic State and to use Turkish territory as part of a training program for Syrian opposition fighters, Obama administration officials said Sunday.

“That’s a new commitment and one that we very much welcome,” Susan E. Rice, President Obama’s national security adviser, said on NBC’s “Meet the Press.”

Defense officials said that they expect clearance to use Incirlik Air Base, a U.S.-built facility about 35 miles inland from the eastern edge of the Mediterranean Sea, near Turkey’s border with Syria, for airstrikes against the Islamist militants. Incirlik is a joint facility where both the Turkish and U.S. air forces operate.

Defense Secretary Chuck Hagel said last week that use of Incirlik for Syria missions was one of the key U.S. requests. It was discussed with Turkish officials during a visit there Thursday and Friday by retired Gen. John Allen, Obama’s special envoy to the anti-Islamic State coalition, and State Department diplomat Brett McGurk.

A Defense Department planning team is expected to travel to Turkey this week to finalize the plans.

Rice said that Turkey has joined Saudi Arabia — a country with which it has strained relations — in agreeing to the training program. “They have said that their facilities inside of Turkey can be used by the coalition forces — American and otherwise — to engage in activities inside of Iraq and Syria,” she said.

U.S. officials have said that it will take several months to vet up to 5,000 opposition fighters, and up to an additional eight months for the training to be completed.

Turkey had been reluctant to sign on to the coalition against the Islamic State, which it believes has diverted attention from the effort to oust Syrian President Bashar al-Assad. Its government has long been critical of delays in the U.S. training program.

In an interview published Sunday in Turkey, Prime Minister Ahmet Davutoglu said that “this training and equipping activity is a delayed one. . . . Frankly speaking, if the United States” and Western countries “had two years ago arrived at the point they have arrived at today and the moderate opposition had been supported . . . ISIL would not have had a space to use and the [Assad] regime would not have had the power to commit massacres.” ISIL is one of several acronyms for the Islamic State.

The United States has resisted Turkey’s call for the coalition to establish a buffer zone along the Turkey-Syria border, where rebels could train and be resupplied and an estimated 1.5 million Syrian refugees now in Turkey could be housed.

“We don’t see it at this point as essential to the goal of degrading and ultimately destroying ISIL,” Rice said, “but we’ll continue to talk to the Turks and entertain any specific proposals that they may have.”

In an interview Sunday on ABC’s “This Week,” Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, said that he had not been asked to set up a no-fly zone. But Dempsey said he anticipated that “there could be circumstances in the future where that would be part of the campaign.”

Although Obama has pledged that there will be no U.S. ground troops in the fight against the Islamic State, which has seized massive amounts of territory in Syria and Iraq, Dempsey said in recent congressional testimony that he could envision circumstances where he would recommend sending U.S.military advisers to accompany front-line Iraqi troops. The advisers are currently restricted to joint Iraqi-U.S. operations centers in Baghdad and Irbil, the capital of Iraq’s Kurdish region.

Asked whether he could see a change in that policy, Dempsey said Sunday that “there will be circumstances when the answer to that question will likely be yes, but I haven’t encountered one right now.”

Asked what those circumstances might be, Dempsey said that when Iraqi troops are ready to go on the offensive against the militants in an attempt to retake the strategic northern Iraqi city of Mosul, “my instinct at this point is that that will require a different kind of advising and assisting because of the complexity of that fight.”

Dempsey revealed Sunday that the United States at one point recently in Iraq had called in Apache helicopters to protect Baghdad’s airport against the Islamic State.

He said on ABC that militants were within “20 or 25 kilometers” of the airport and had “overrun the Iraqi unit. It was a straight shot to the airport. So we’re not going to allow that to happen. We need that airport.”

Up to 200,000 new refugees have fled into Turkey in recent weeks from the Syrian border town of Kobane in the face of an ongoing attack by the Islamic State. Kurdish defenders of the town, surrounded on three sides by the militants, were said to be holding their own Sunday. Coalition aircraft from the United States, Saudi Arabia and Jordan conducted three separate airstrikes “in Kobane,” according to a release by the U.S. Central Command.

On Friday, the United Nations called on Turkey, which has sealed its border adjacent to Kobane, to allow Kurds on the Turkish side to cross over and help defend the town. On Saturday, Turkish Foreign Minister Mevlut Cavusogly rejected that plea, saying that “sending civilians to the war is a crime. We cannot risk the lives of these people.”

In Iraq, the Associated Press reported that a triple-suicide bombing Sunday in Diyala province killed at least 58 people and that the Islamic State claimed it had ordered the attack, carried out by three foreign jihadists. The authenticity of the online statement could not be independently verified, but it was posted on a Twitter account frequently used by the militant group.

Also, authorities said a roadside bomb killed the police chief of the western Anbar province, according to the AP.

Sebastian Payne contributed to this report.