EXECUTIVE SUMMARY: Discounting the sincerity of Turkish President Erdoğan's fiercely anti-western rhetoric ahead of the April 16 referendum is akin to disregarding bitter facts about once staunch NATO ally Turkey. NATO's deepening "Turkey problem" is contained in the country's Islamist ideology, conspicuous "un-likemindedness", and democratic anomalies, which stand against NATO's founding values of safeguarding freedom and the principles of democracy, individual liberty, and rule of law.

Turkey-optimists in the western world tend to minimize President Recep Tayyip Erdoğan's explosively chauvinistic, anti-western rhetoric before the April 16 referendum, which gave him sweeping new powers. They argue that he was merely attempting to appeal to an increasingly anti-western audience. That view is misleading, to put it mildly.

Erdoğan's deep-rooted Islamist ideology and slavery to the anti-western populism he has so vigorously created make Turkey the odd one out in the West, including in NATO.

A few years ago, as NATO's combat mission in Afghanistan came to a close, some of the conventional challenges the alliance faced included:

A transatlantic austerity that sparked major cuts in defense budgets, pruning allied conventional force and operational capabilities

A need, after Afghanistan and with Georgia and Ukraine still bitterly fresh, to shift focus towards conventional forces and move from a security understanding towards a defense understanding

The reality that some members were liabilities rather than assets and that the adjustment of new members was taking place very slowly

The risk of disruptive technologies that could enable individuals or small groups to use force in ways previously exclusive to states

Shifting demographics, like aging populations and diminishing recruiting pools

Rising powers in Asia and Eurasia and their future trajectories

A paradigm shift from deterrence towards prevention and resilience

The Turkey-optimists were never particularly concerned about Ankara, but even the realists largely failed to predict that as Eurasia rose, Turkey's corresponding perception of NATO as a weakened security alliance would turn it from a staunch member into an "a la carte" member. Ankara's political goals have diverged from those of NATO, leaving the alliance with a serious "Turkey problem".

Taking refuge from the August heat at Alexei Kosygin's Kremlin banquette back in Cold War-stricken 1965, Turkish Prime Minister Suat Hayri Urguplu said "he was very pleased to be witness to the gradual and confident development of mutual understanding with the Soviet Union." The next day, an Istanbul daily commented, "Improvement of Turkey's relations with the Soviets is fine on one condition: that we always remain an ally of the United States and in NATO."

Forty-two years later, in 2007, bigwigs in Turkey's defense bureaucracy were seriously considering a non-aggression pact with Russia. In April 2009, military teams from Turkey and Bashar al-Assad's Syria crossed the border and visited outposts during joint military drills. That was the first time a NATO army had exercised with Syria's.

In September 2010, Turkish and Chinese aircraft conducted joint exercises in Turkish airspace. That, too, was a first for a NATO air force. In 2011, a Transatlantic Trends survey revealed that Turkey was the NATO member with the lowest support for the alliance: just 37% (down from 53% in 2004). The same year, before finally providing NATO forces with logistical support, then prime minister Erdoğan angrily asked, "What business can NATO have in Libya?"

Also in 2011, the Turkish government announced plans to build a ballistic missile with a range of 2,500 kilometers. In 2012, Turkey joined the Shanghai Cooperation Organization (SCO) as a dialogue partner. (Other dialogue partners were Belarus and Sri Lanka; observers were Afghanistan, India, Pakistan, Iran, and Mongolia.) Since then, Erdoğan has said more than once that Ankara will abandon its quest to join the EU if it is offered full membership in the SCO.

In September 2013, Turkey announced it had selected a Chinese company for the construction of its first long-range air and anti-missile defense system. Turkish officials said local engineering would make the Chinese system interoperable with the US and NATO assets deployed on Turkish soil. (Later, this contract was scrapped.)

And in 2014, the Financial Act Task Force, an international body setting global rules and standards for combating terrorist financing, ruled that Turkey should remain on its gray list, along with Algeria, Ecuador, Ethiopia, Myanmar, Pakistan, Syria, and Yemen. Experts said troubling questions remained about Ankara's relationships with Iranian gold traders, Hamas leaders, al-Qaeda in Syria, and persons designated under the US sanctions regime.

Beginning in 2015, Turkey came under international suspicion for systematically and clandestinely extending support to various jihadist groups in Syria, including, allegedly, Islamic State (IS). That support is speculated to have included logistics and arms. In the Syrian theater, Turkey and its NATO allies have divergent goals: the West's primary goal has been to fight IS, while Turkey's has been to topple Syria's Nusaryi (non-Sunni) president, Bashar al-Assad, and install a Sunni, pro-Turkey regime of Islamists in his place.

The US has made clear that it will fight IS, especially in Raqqa, its so-called capital, with the help of ground troops made up of Syrian Kurds – people Ankara considers terrorists. In northern Syria, NATO and Turkey have different aims: NATO wants to help in the allied fight against IS, while Turkey wants to fight the Kurds, now part of the anti-IS campaign. Ankara's objective is to halt the construction of a Kurdish belt along Turkey's southern border with Syria.

The West praised Ankara when it stopped contract negotiations with the Chinese for its air defense architecture, and Western lobbyists were cheered when Turkey discreetly negotiated with US and European weapons makers for the same purpose. But all of a sudden, Turkey announced early this year that it was close to a deal to buy Russian-made S-400 air defense systems. (Iran could have been an attractive choice for co-production were it not a Shiite enemy in the eyes of Turkey's Sunni elite.)

NATO experts have at long last begun to ask: Can Turkey, with its huge democratic deficit, be a reliable partner? After all, the founding values of NATO are the safeguarding of freedom and the principles of democracy, individual liberty, and rule of law. In today's Turkey, the upholding of these values can earn one a "terrorist" tag and a long jail sentence.

NATO's Turkey problem got deeper at the alliance's Brussels summit in May, when Ankara vetoed NATO's cooperation with Austria, a move that blocked the alliance's partnership activities with 41 countries. The move was in retaliation against Austria's objection to Turkish membership in the EU. Erdoğan said of the Turkish veto, "Those who veto get vetoed." In other words, he thinks he can fairly punish NATO because an EU member state objects to Turkey's membership due to its democratic anomalies.

On June 7, German Defense Minister Ursula von der Leyen said that Germany will pull all of its 270 troops stationed at the Incirlik base, as well as Tornado reconnaissance aircraft and a refuelling plane, out of Turkey. All German assets, including troops and platforms, will be removed to Jordan over the next two months.

With a completely different, religious (pro-Sunni), and revisionist (neo-Ottoman) agenda, Turkey – once an important ally in Cold War NATO – has become a liability for the alliance. Blame it on its newfound un-likemindedness.