The strategically critical U.S.-Turkey relationship is coming under increasing strain as authorities in Ankara crack down on alleged coup plotters and sympathizers.
Washington is caught between expressing alarm about increasingly authoritarian measures being taken under Turkey's state of emergency and showing support for a democratically elected government that fought off a military putsch.
A further source of irritation is persistent rumors in Turkey that the United States played a role in the attempted coup, something State Department spokesman John Kirby characterized on Thursday as "ludicrous."
Turkey's government has ordered more than 130 media outlets — TV channels, radio stations, newspapers and news agencies — to close, and approximately 90 journalists have either been arrested or ordered detained.
"We're obviously deeply concerned," said Kirby, who continued to stress that "Turkey matters to us as a friend and ally, and their democracy matters to us."
About 1,700 military personnel have been dismissed, including 150 generals and admirals suspected of ties to the uprising.
Ankara is a critical American ally in the fight against the so-called Islamic State group operating in Iraq and Syria, both of which border Turkey, a NATO member.
Incirlik Air Base, shared with the Turkish military, is used for U.S. airstrikes against Islamic State and is also a key hub for airlift operations.
Many of the Turkish generals the U.S. military has been working with in the fight against IS are now believed to be imprisoned in the aftermath of the coup attempt, according to Army General Joseph Votel of the U.S. Central Command, speaking Thursday at the Aspen Security Forum.
Votel expressed concern about the arrests having an impact on the anti-terrorism operations, saying the Turkish military is "absolutely vital to what we are doing."
Added U.S. National Intelligence Director James Clapper, from the same forum, "Many of our interlocutors have been purged or arrested. There's no question this is going to set back and make more difficult cooperation with the Turks."
Under the three-month state of emergency enacted by Turkey, tens of thousands of people have been suspended from their jobs or placed under investigation since the July 15 coup attempt.
Turkey's foreign minister and other officials warned this week that ties will be damaged if Washington declines an extradition request for Fethullah Gulen, a Muslim cleric living in the U.S. since 1999, whom Ankara considers the coup mastermind.
Senior U.S. officials have said the request will be considered if Turkey submits legitimate evidence of Gulen's involvement.
President Recep Tayyip Erdogan and others have made clear that they expect Gulen, head of an influential transnational religious and social movement, to be convicted if put on trial for treason. The Turkish president also is seeking restoration of the death penalty, citing popular opinion.
The European Union has said executions would destroy Turkey's application to join the EU, which Ankara has been pressing since 2005.
In remarks broadcast live on Haberturk television Thursday, the country's justice minister, Bekir Bozdag, said if the coup had been successful Gulen would have returned home. He contended the exiled cleric "had been preparing for this for the last 40 years."
The coup, Bozdag added, would have led to setting aside the constitution and "the regime would have been changed."
Bozdag also contended that Gulen, a 75-year-old former imam who lives in the U.S. state of Pennsylvania, could flee to Australia, Canada, Egypt, Mexico or South Africa.
Gulen has denied any involvement with what he terms a "horrific failed coup."
Turkey's foreign minister, Melvut Cavusoglu, is demanding that Germany extradite Gulen followers in that country, according to broadcaster CNN Turk. The foreign minister alleged that judges and prosecutors who are followers of Gulen are currently in Germany, which has a significant Turkish minority population.
The Turkish president's ruling AK party and opposition groups that have bitterly opposed Erdogan have shown signs of ending their disagreements since the coup attempt, and are trying to reach a consensus on how to remove Gulen supporters from state institutions.
The Turkish government is casting a wide, worldwide net in its efforts to bring down Gulen supporters. Diplomats have even asked Thailand to investigate businesses in the Southeast Asian country that they allege are tied to Gulen, including the Thai Turkish Business Association.
About 700 Turks are believed to live in Thailand. The kingdom's foreign minister has said that if the business association is found to be operating in support of a terrorist network, then legal action will be taken, Turkey's Anadolu news agency reported.
VOA National Security Correspondent Jeff Seldin contributed to this report.