Read: The U.S. moves out, and Turkey moves in

This soon became a case of more allies, more problems. When Turkey invaded Cyprus in 1974 following a Greece-backed military coup, the two allies came into direct conflict; in fact, Greece left NATO over it, before later rejoining. Later, the U.S. flew bombing raids on Iraq from Turkey’s Incirlik Air Base during the 1990–91 Gulf War; in 2003, though, Turkey refused to station U.S. troops on its territory to attack Baghdad. (Other U.S. allies, namely France and Germany, also opposed the 2003 Iraq War, though France was not fully participating in NATO at the time.) As for that whole democratic-values thing, the military stepped in to run the country about every decade or so.

But by the time anti-government protests swept Arab countries in 2011, Turkey looked like a model of stability and Islamic democracy. In an interview with NATO Review in 2012 marking 60 years of Turkey being in NATO, then–Turkish Defense Minister Ismet Yilmaz said that in joining the alliance, Turkey had made its direction, and its security, “the same as the West’s.” He went on: “This was not a decision Turkey took only in 1952. This was the consequence of Turkey supporting Western values. Let’s not say Western—universal values, which are democracy, human rights, and core values of human rights based on the rule of law.” Turkey was even negotiating for membership in the European Union.

Which all now seems a bit rich, given that the current leader, Recep Tayyip Erdoğan, a self-avowed champion of the Muslim Brotherhood, has changed the constitution, rerun elections that didn’t favor his political party, and led a crackdown on journalists and political dissenters, as well as a purge of thousands suspected of involvement in a failed 2016 coup. Even on the interests front—Incirlik Air Base has been central to U.S. counterterrorism efforts in the ISIS era—hitches came up. The Turkish government did little to rein in ISIS fighters transiting its territory to join the battles in Iraq and Syria; some ISIS members even passed through Turkey to carry out attacks in Europe. Erdoğan’s government has bought Russian air defenses over vigorous American objections and in the face of sanctions threats, and as of this week, the Turkish government ditched an agreement that U.S. officials had hoped would keep the peace in northeastern Syria.

Read: The Trump administration doesn’t care about allies

“About 10 years ago, you couldn’t swing a dead cat in Washington and not hit somebody who wouldn’t say, ‘Oh, Turkey’s a great ally’ … Now everyone’s mad at Turkey,” Cook said.

Hence the questions now about whether the alliance is even worth it. Senators Lindsey Graham and Chris Van Hollen are pushing bipartisan legislation to sanction Turkey over its Syria incursion; Graham has also floated suspending Turkey from NATO altogether. (There’s actually no clear legislative way to do this—the NATO charter doesn’t contemplate kicking out members, though members can leave on their own, as Greece did over its dispute with Turkey.) France’s EU-affairs minister, too, has said that NATO suspension is “on the table.”