Turkey launches an inquiry focusing on the state-owned Halkbank, whose chief executive has been arrested in the case on suspicion of bribery. The bank has also long been suspected by the United States of helping Iran evade sanctions over its nuclear program by using gold to purchase Iranian oil and gas. http://www.nytimes.com/2013/12/24/world/europe/growing-mistrust-between-us-and-turkey-is-played-out-in-public.html?pagewanted=2&_r=0&ref=world

This year, 47 American lawmakers wrote a letter, which has been re-aired in the Turkish news media over the past week, to urge Mr. Kerry to push the Turks for closer monitoring of the relationship between Iran and Halkbank.

“These guys were massive sanctions busters,” said Steven A. Cook, a fellow at the Council on Foreign Relations and an expert on Turkey. “It’s been a sore point between Washington and Ankara.”

The other element is that the inquiry, which has targeted several people in the prime minister’s circle, has been linked to Fethullah Gulen, a popular Muslim cleric who once was a close ally of the prime minister but is now a fierce political enemy.

His life of exile in Pennsylvania has led to conspiracy theories here, and his followers are believed to occupy important positions within the police and judiciary, which are carrying out the corruption inquiry.

The investigation into Halkbank, Mr. Cook said, might “be part of a Gulenist effort to demonstrate to the U.S. that maybe Erdogan is not a reliable partner.”

It was just this May that Mr. Obama stood in the Rose Garden with Mr. Erdogan and said to reporters, “I value so much the partnership that I’ve been able to develop with Prime Minister Erdogan.” Now, when Mr. Erdogan speaks caustically about American scheming, officials are left to wonder if Mr. Erdogan really believes what he says, or whether he is using such talk as a populist ploy.

Suspicion of foreign meddling is deeply ingrained here, running back to the last days of the Ottoman Empire, when the region was, Mr. Cagaptay said, “a playing field for various foreign actors.”

Mr. Cook said that in Washington “there is an intellectual understanding” that Turkish officials fall back on such conspiracy theories at times of crisis. Yet, he said that among some American policy makers, “there has been a reassessment of Erdogan and his temperament.”

As with most alliances, the relationship has had its ebbs and flows over the past generation. But the current tension has a facet that was missing even in some of the most fraught episodes between the two countries, such as in 2003 when Turkey refused permission for the American military to invade Iraq across its borders, and in 2010 when it voted against United Nations sanctions on Iran.

“It’s the first time in memory that pro-government newspapers are calling for the American ambassador to leave,” Mr. Cagaptay said. “That’s unique.”