As part of the project A Nation Engaged, NPR and member stations are exploring America's role in the world heading into the presidential election.
For more than a decade, U.S. foreign policy has centered on military action in the Middle East. Often overlooked, but still critical, is U.S. diplomacy. It's a slow and often frustrating art. It can also involve unpopular compromises with allies and rivals.
But there's no way around it. Consider Turkey, with a strategic location that makes it important in Syria, Iraq and the migrant crisis. But the U.S. and Turkey have had a roller-coaster relationship that took a sharp downward turn after an attempted coup last month against President Recep Tayyip Erdogan.
Some Turks, including a Cabinet minister, accused the U.S. of being behind the uprising, though they provided no evidence. And America watched with dismay as the Turkish government, which it once hailed as a democratic model, arrested thousands, sacked tens of thousands more from their jobs and squashed dissent.
But just last week came signs that Ankara and Washington were getting back on the same page, in both military and diplomatic terms. Turkish tanks rolled across the border into Syria with Turkish special forces and Free Syrian Army rebels to clear Islamic State forces away from the border area.
The roar of artillery was sweet music to the ears of U.S. military officials, who have long pushed Turkey to do more against the militants next door.
Hours later, Vice President Biden was in Ankara, heaping American praise on Turkey's controversial leader, Erdogan, and declaring undying friendship.
"Let me say it again: You have no greater friend than the United States of America," said Biden. "We've seen that borne out each time we stand together, face down threats to our shared security and our common values."
But few people think the visit did much more than temporarily patch up a complicated relationship. It's a good example of how Washington relies on its allies in troubled regions to help advance its interests. But allies have agendas of their own that make friction all but inevitable.
Disagreement over the Iraq War
In Turkey's case, that became crystal clear during the run-up to the 2003 U.S.-led invasion of Iraq. Turkey opposed it, worried about violence spilling back over its borders. But the Pentagon was determined to send in troops via Turkey.
Turkey's man in Washington in those days was Ambassador Faruk Logoglu. He remembers spending more time with military officers than diplomats and says the conversation largely went in one direction.
The U.S. military "really wanted to put American soldiers into Iraq through Turkey, and they didn't want to hear anything else," he recalls. "This is what they wanted, and they wanted it now — they were in a hurry."
Turkey said no, and the U.S. troops had to be rerouted through Kuwait. A few months later, when American forces came across Turkish special forces in the northern city of Kirkuk, they hooded, handcuffed and hauled them away for interrogation. U.S.-Turkey relations went into the deep freeze.
Right about then, America named a new ambassador to Turkey, Eric Edelman, a former adviser to Vice President Dick Cheney who to many Turks was the embodiment of what they saw as America's "my way or the highway" approach to Mideast policy.
Edelman still remembers how his predecessor greeted him.
"He told me, 'You're very lucky. You're arriving at the absolute nadir of the Turkish-American relationship. Things can only go up from here,' " he says, before adding with a laugh: "That turned out to be not completely accurate."
Edelman went on to be labeled "the worst U.S. ambassador in history" by pro-government Turkish newspaper columnists. (It's a title since bestowed on at least one of his successors.) Edelman remembers waiting weeks for meetings with Turkish leaders.
A crucial air base
But even when the relationship sours precariously, one symbol of Turkish-American cooperation endures. It's deep in southeast Turkey, just 70 miles from the Syrian border.
On a recent afternoon, the roar of warplanes fills the air outside the Incirlik Air Base. They may be headed for Syria — this is where many U.S. fighter jets and surveillance aircraft launch their anti-ISIS missions.
Incirlik has been used by the U.S. Air Force and other NATO allies for decades. It was built by the U.S. Army Corps of Engineers in the early 1950s, with the Cold War underway. The Air Force saw it as an ideal staging area for missions in the Mideast and beyond.
Incirlik village, adjacent to the base, is where generations of American military families grew up alongside Turks. They rented houses from Turks off the base, their children played together, they shopped in Turkish markets. Local resident Sadat Kayhan, who like many people here works on the base, says from the start, everyone got along fine.
He thinks back to the 1990s, when Americans were everywhere.
"We took them to all the tourist areas," Kayhan says. "We would ride in cars with big American eagles on them. Everyone knew we were with the Americans and no one would bother us."
Americans must remain on base
But in recent years, that intermingling has ended. Turks say the chill started after the Iraq invasion in 2003, and these days, after a string of terrorist attacks in southeast Turkey, Americans are restricted to the base.
Many military family members have been sent home, the off-base houses they rented sit empty, and shops that catered to them are boarded up, for sale or rent.
Two retirees who worked for decades on the base say there's no reason for the Americans to be cut off.
"There was life, it was fun, people all around," says Mustafa Tutkal.
"It shouldn't be locked down," adds Jumali Yamur, who thinks the base restrictions are more about political disagreements than terrorism.
There are things the U.S. can offer, including support for Turkey's essentially stalled bid to join the European Union. The U.S. could help rein in the ambitions of Kurdish factions — longtime Turkish adversaries — in Syria and Iraq. And trade and investment would be welcomed in Turkey's fragile economy.
On the other hand, Washington is concerned by Erdogan's crackdown on the media, freedom of expression and civil liberties.
A growing list of issues
Edelman, the former ambassador, thinks the relationship is in for an extended bumpy period. As with the last crisis, when he was in Ankara, he thinks it's vital that Turkish politicians don't go too far in whipping up anti-American feelings.
"My concern was then, when I was there, and I repeatedly told the government, 'You know, if you guys don't tamp this down a bit, some American is going to get hurt. And then there's really going to be hell to pay,' " he says.
For its part, Turkey wants the U.S. to extradite an elderly Islamic cleric based in Pennsylvania named Fetullah Gulen, whom the Turkish government accuses of orchestrating the failed July 15 coup that left 240 dead. And if the U.S. doesn't do that, or it pressures Turkey on human rights, Turkey could turn eastward to boost relations with Russia or Iran.
But Logoglu, the former Turkish ambassador, says Turkey's basic alignment with the West — a founding principle of the Turkish republic — will keep the relationship from breaking down completely.
"No, I think it's not going to be an earthquake type of rupture," he says. "This crisis will also be weathered."
Logoglu's prescription: This is a diplomatic crisis, so the solution should be more and better diplomacy.