As Turkey mulls letting Russia use an air base that houses American nuclear weapons, U.S. officials are using flattering terms to characterize its relationship with the NATO ally.

Incirlik air base has been a key NATO outpost for decades, but Turkish President Recep Tayyip Erdogan has made some ominous moves regarding the base in the wake of a failed coup attempt that he blamed on the United States.

External power to the base, which houses about 2,500 U.S. military personnel and dozens of tactical nuclear weapons, was cut for a week after the coup attempt. Turkish government officials have talked openly of allowing Russia to use the base.

That has Obama administration officials striking a conciliatory tone. "We deeply appreciate, frankly, Turkey allowing us to use Incirlik because it allows us to carry out airstrikes in close proximity and support for the Syrian Democratic Forces that are fighting in northern Syria and we want to continue with that relationship," State Department spokesman Mark Toner said Tuesday.

Those remarks echoed the statement made by the top American general in Europe following a visit to the Turkish capital. "[Turkey] sits at the crossroads of the many challenges we face in Europe, from the refugee crisis, to terrorism, to human trafficking," Army Gen. Curtis Scaparrotti, the top U.S. general in Europe, said Monday.

"We are thankful for their leadership and contributions in each of these areas, and for access they have granted us to their bases, which are critical to our operations."

Vice President Joe Biden plans to visit Turkey this week in an additional effort to ease tensions with Ankara. In the meantime, Russian President Vladimir Putin and other officials are working to strengthen their ties to Turkey, which is a NATO member.

"It just remains to come to an agreement with Erdogan that we get the NATO base Incirlik as our primary air base," Igor Morozov, a Russian senator, told a media outlet in his country last week. "You'll see, the next base will be Incirlik."

That idea received apparent confirmation from a Turkish official. "If necessary, the Incirlik base can be used [by the Russians]," Turkish Prime Minister Binali Yildirim told reporters over the weekend.

The State Department demurred when asked how Russian access to the base would affect the U.S. forces deployed there, while opening the door to U.S.-approved cooperation between Turkey and Russia if Putin would agree to stop bombing civilians and opponents of Syrian President Bashar Assad.

"We have in our private diplomatic conversations with Turkey sought clarity on what the implications of those [comments] might be," Toner said. "As much as we can have a better and more constructive relationship with regards to Syria, we would certainly want the same between Turkey and Russia. For our part, we're not there yet."