Opinion | NATO’s internal standoff is a gift to Putin

That impasse is bound up in a matrix of problems, not least Turkish President Recep Tayyip Erdogan’s domestic political challenges, a mess largely of his own making. Mr. Erdogan is a tireless haggler and certain to use the leverage he has to extract concessions from his NATO allies and excite his nationalist base ahead of Turkey’s elections, scheduled for June.

Still, it would be dangerous to dismiss his obstruction as temporary posturing or to assume the problem will disappear if Mr. Erdogan wins the elections despite mismanaging the country’s skyrocketing inflation and the resulting economic turmoil. Resolving the standoff will require sustained diplomacy and, possibly, real concessions, some of them in Washington’s power to make. President Biden and Congress can play a key part in that. They should, because whatever heartburn Turkey presents to NATO, it is a powerful and indispensable alliance member, and the consequences of enlarging NATO’s membership — or failing to do so — are titanic.

Sweden and Finland are modest-sized countries — together they would add less than 2 percent to NATO’s collective population of roughly 950 million — but they would pack an outsize punch. Their entry would represent a grievous strategic defeat for Russian President Vladimir Putin, vastly expanding the Western alliance territory along his border.

More than any other tangible move available to Washington and its European allies, the expansion would drive home the depth of the Kremlin’s folly in mounting a blood-soaked invasion of a sovereign nation that represented no military threat to Moscow. And it would extend NATO’s security umbrella to a pair of valued partners that are justly nervous over Russia’s proven willingness to unleash a full-scale regional war and have abandoned decades of neutrality to apply jointly for membership in the alliance.

Mr. Erdogan has taken advantage of that application — as well as NATO rules that give any member a veto on expansion — to amplify Turkey’s grievances with the two Nordic candidates and the alliance generally, including the United States. Some of those grievances are rooted in Turkey’s own security concerns. Others reflect the disconnect between the intolerant and increasingly despotic state Mr. Erdogan has built and the robust democracies buttressed by vibrant civil societies in other NATO member states, as well as Sweden and Finland.

Turkey’s loudest complaint is the toughest to satisfy. Mr. Erdogan has been adamant that Sweden, whose Kurdish population is around 100,000, crack down on alleged activists and sympathizers linked to the Kurdistan Workers’ Party, or PKK, which has carried out terrorist attacks in Turkey; Ankara as well as the United States and European Union regard it as a terrorist organization. The trouble is partly definitional: In some cases, Turkey has demanded the extradition of Kurds and other anti-Erdogan activists whose cases have been adjudicated by Swedish courts or do not qualify as terrorists by Western standards. In the case of the one person whose extradition Mr. Erdogan has publicly demanded — an exiled journalist he accuses of supporting a 2016 coup aimed at toppling him — the Swedish courts have refused. In any event, Mr. Erdogan cannot reasonably expect a Western democracy to cast aside its laws and judicial procedures to hand over activists on the grounds that he considers them enemies.

Another Turkish demand, that the Nordic countries lift their prohibition on selling arms to Ankara, seems on its way to resolution. The ban, also imposed by other European countries, was put in place in 2019 after Turkey launched attacks inside Syria against a PKK-affiliated Kurdish militia, backed by the United States and its European allies, that was key to the Islamic State’s military defeat. Keeping the priority of NATO accession in their sights, Sweden has resumed some arms sales to Turkey, and Finland would be wise to follow suit.

A much larger arms issue is Turkey’s $20 billion request to expand and modernize its existing fleet of U.S.-made F-16 fighter jets. Despite support from the Biden administration, the sale has been blocked on Capitol Hill, apparently over human rights concerns in Turkey and at the behest of lawmakers sympathetic to Greece, which opposes the deal. The congressional roadblock is myopic, and the rationale for it pales against a big-picture consideration of Turkey’s vital role in NATO and its expansion.

There’s no question Turkey, which joined NATO in 1952, just three years after the alliance’s birth, has been at times an awkward partner for its allies. Mr. Erdogan has compounded those challenges since coming to power in 2014, forging closer ties with Russia even as Mr. Putin sent troops into Ukraine. In 2019, over heated objections from the Trump administration, Turkey deployed S-400 missiles, a Russian air defense system that the United States feared could compromise the crown jewel of NATO’s own arsenal, the F-35 Joint Strike Fighter. Mr. Erdogan’s insistence on that move was rightly seen in Washington as a betrayal.

Resentments and colliding interests are the price of any lasting alliance. In the end, Turkey and its NATO allies are vital to each other’s security and to containing and ultimately defeating Russian aggression. The alliance needs Turkey, which has been a bulwark to the West’s defense against Iran, equipped Ukraine with drones and other arms, and closed off the Black Sea to Russian naval reinforcements. Equally, Turkey, which endured a tense standoff with Moscow in 2015 after shooting down a Russian fighter plane in Turkish airspace, would be wise not to further alienate its NATO allies and jeopardize the insurance policy they provide.

Mr. Putin is the only winner in the showdown over allowing Sweden and Finland to join NATO. The sooner Turkey and its partners come to terms, the better for the alliance.