In April, as the world was occupied with Vladimir Putin’s invasion of Ukraine, a NATO member launched an attack on two of its neighboring territories. In a bombing campaign, Turkey targeted the camps of Kurdish militants in Iraq and Syria, inflicting damage on shelters, ammunition depots and bases.

The irony went largely unnoticed. That’s hardly a surprise: For a long time, the Western world has turned a blind eye to Turkey’s heavy-handed treatment of the Kurds. Across decades, the Turkish state has persecuted the Kurdish minority — about 18 percent of the population — with devastating zeal. Thousands have perished and around a million have been displaced in a campaign of severe internal repression. But Western nations, except for a brief spell when Kurdish resistance was holding back an ascendant Islamic State, have rarely seemed to care.

Turkey’s treatment of the Kurds is now center stage — but not because allies have woken up to the injustice of Kurds’ systematic oppression. Instead, it’s because Turkey is effectively threatening to block the admittance of Finland and Sweden to NATO unless they agree to crack down on Kurdish militants. For President Recep Tayyip Erdogan of Turkey, seeing an opportunity to further cement his nationalist agenda, it’s a bold gambit. The tepid response from NATO allies so far suggests he might be successful.

However the situation shakes out, it’s deeply revealing. For Turkey, it underlines once again the vigor with which Mr. Erdogan is keen to stamp out the Kurds while asserting the country as a regional power. For the alliance itself, the impasse brings to light facts currently obscured by its makeover as a purely defensive organization. NATO, which has long acquiesced in the persecution of the Kurds, is far from a force for peace. And Turkey, a member since 1952, proves it.

Turkey’s conflict with the Kurds goes back at least to the late 19th century, when Ottoman centralization led to tribal uprisings. The initial two decades of the Turkish Republic, founded in 1923, involved the denial of Kurdish identity, autonomy and language, all of which were mainstays of the Ottoman Empire. Rebellions ensued but were forcibly put down. After remaining largely dormant in the 1940s and 1950s, Kurdish militancy then experienced a revival, under revolutionary banners. The Kurdistan Workers’ Party, or P.K.K., emerged in this atmosphere.

The organization is designated a terrorist group by Turkey, the United States and the European Union — and its methods are indeed violent. Across four decades of conflict, the P.K.K. has contributed to the bloodshed and is responsible for the deaths of civilians as well as security officials. Yet Turkey’s militaristic approach to the Kurdish issue has left little room for other, more conciliatory Kurdish organizations.

The country experienced a spring of Kurdish activism in the late 1960s and 1970s, when many left-wing Turkish movements and organizations also expressed solidarity with the Kurds. But a coup d’état in 1980 heavily crushed these forces, with the exception of the P.K.K., most of whose camps were already outside Turkey. In the years after the coup, the heavy torture suffered by Kurdish activists of various organizations swelled the ranks of the P.K.K. More embittered against the Turkish state than ever, many activists saw no other effective home for their struggle.

Things today aren’t much better: Peaceful forms of Kurdish activism — such as those organized by the legal Peoples’ Democratic Party, or H.D.P. — are under constant attack, accused of affiliation with the P.K.K. The government also claims that the P.K.K. is in cahoots with the Gulen movement, a former ally of the ruling party the government accuses of orchestrating a failed coup attempt in 2016. It is members of these two groups who Mr. Erdogan is demanding Sweden and Finland give up.

Where was NATO in all of this? The 1980 military intervention, at least passively endorsed by the alliance, was led by Kenan Evren, a commander in NATO’s counter-guerilla forces. Western countries kept on providing ample support for campaigns against the Kurds in the following years, even during the exceptionally violent clashes of 1993-95. As hostilities resumed in the 2010s, the West largely neglected internal waves of repression and Turkey’s recurrent incursions into Syria and Iraq, where Kurds have long sought refuge.

If such enabling silence is so persistent, why did Mr. Erdogan choose this particular time to ramp up military adventures? The answer is simple: Elections are around the corner, and the government, overseeing the country’s worst economic crisis in two decades, is counting on jingoism as a remedy for national ills. The ruling party has accordingly ratcheted up its moves against the Kurds, with imprisonment of politicians and journalists, military campaigns abroad and bans on concerts and plays at home.

Russia’s invasion of Ukraine has apparently further emboldened Mr. Erdogan. It has allowed Turkey to pose as a friend to the West, earning praise for its early blockade of the Black Sea while continuing to pursue its repressive agenda. What’s more, by pushing Sweden and Finland — perceived to be longtime harborers of Kurdish militants — toward NATO, the war has handed Turkey a golden opportunity.

If the United States were to pressure the two countries to accept Turkey’s demands, as Secretary of State Antony Blinken has suggested might happen, it would be more than a policing victory. It would be a rare symbolic triumph. Bombings and cultural bans would be nothing compared with an international admission, sealed by the world’s most powerful country, that Kurdish rights can be waved aside.

It’s tempting to see Turkey as an exceptionally bellicose state. Labeled the “sick man of Europe” in the final days of the Ottoman Empire, the country now appears to be the continent’s belligerent man. But it’s wrong to look at the country in isolation. Mr. Erdogan’s aggression is not his alone. It is enabled, encouraged and buttressed by Western countries, as well as Russia.

In Turkey, this is a provocative claim: The authorities want their citizens, and the world, to believe that “foreigners” and “outside powers” have always supportedKurdish separatism. This quite popular but highly twisted perception of reality says nothing about the weapons, logistical support and consent other countries have abundantly provided in the killing of Kurds.

The United States supplied weapons to Syrian Kurds during their fight against the Islamic State, it’s true. But that’s dwarfed by the sophistication and amount of military equipment that Turkey, home to NATO’s second-largest military, secures thanks to being part of the Western alliance.

The truth is that Turkey’s aggression has gone hand in hand with NATO acceptance, even complicity. It’s no use for Western countries to be lecturing Turkey, or Turkey complaining of Western hypocrisy: They are in it together. Whatever happens with the alliance’s expansion — whether the Kurds are sacrificed on the altar of geopolitical expediency or not — this should be a moment of clarity. In a world of war, no country has a monopoly on violence.