For the US, the group was a critical ally in the campaign to defeat Islamic State in Syria and remains an important force keeping the jihadists from rising up again.
Turkey, a US ally within NATO, views it as a terrorist threat.
The group is the People’s Protection Units, or YPG, a militia in Syria made up mostly of fighters representing the minority Kurdish community.
Disagreements over the YPG have repeatedly stressed relations between Turkey and the US and threaten to provoke Turkey’s veto of a proposed expansion of the North Atlantic Treaty Organization.
What is the YPG?
As the armed wing of the Kurdish Democratic Union Party of Syria, it seeks autonomy for Syria’s Kurds and has shown a willingness to work with any power capable of advancing that goal.
The party itself was formed in 2003 as an offshoot of the PKK, a group that seeks an autonomous region for Kurds inside Turkey.
The PKK has fought Turkish forces on and off since 1984 and is outlawed by Turkey and considered a terrorist organization by the US and the European Union.
Turkey views the YPG, whose ranks are thought to include tens of thousands of fighters, as a security threat due to its ties to the PKK.
What was the YPG’s role in the Syria war?
The YPG wasn’t part of the Free Syrian Army, the Western-backed coalition that was the main opponent of Syrian President Bashar al-Assad’s regime in the early years of the country’s civil war.
But YPG members formed the backbone of the Syrian Democratic Forces, created in 2015 under US auspices to fight Islamic State, the violent movement that at one time controlled a chunk of territory in Iraq and Syria as big as Iceland.
In 2019, the final Islamic State stronghold fell.
Afterward, the Syrian Kurds and Arabs allied with them formed an autonomous zone in the northeast of the country that is aligned neither with Assad’s government nor with its opposition.
How did Turkey respond?
The Turkish government strongly objected to the US arming the Syrian Kurds.
In response to territorial gains by the YPG, Turkish forces have repeatedly made incursions into Syria to set them back.
In mid-November, Turkey carried out air strikes against the group in retaliation for a deadly bombing that targeted civilians in Istanbul.
Turkey’s interior ministry blamed the bombing on the PKK and its Syrian affiliate.
What do Syrian Kurds have to do with NATO’s expansion?
When Sweden and Finland moved toward applying to join NATO in response to Russia’s invasion of Ukraine, Turkish President Recep Tayyip Erdogan expressed reservations, throwing their candidacy in doubt since the alliance admits new members only by unanimous consent.
Turkey criticized Swedish officials for meeting with Kurdish politicians, citing an encounter between Foreign Minister Ann Linde and Elham Ahmad, who represents the political wing of the YPG.
Another focus of tension was the Syrian Democratic Council, the political arm of a group of Kurdish-dominated forces in northern Syria.
Turkey says the SDC is dominated by terrorists.
Sweden says it cooperates with the SDC, but not with the YPG.
Sweden and Finland, which got caught in the crossfire, have pledged to address Turkey’s concerns.
Who are the Kurds?
They are an Indo-European people, mostly Sunni Muslims, numbering about 30 million, whose homeland is divided among Turkey, Syria, Iraq and Iran.
Kurds have been persecuted in those countries in a variety of ways: stripped of their citizenship, excluded from some professions, barred from giving their children certain names and restricted in speaking their own language.
They’ve pushed for equal rights and autonomy over their affairs and periodically rebelled.
National authorities have responded at times severely, expelling Kurds from their villages in Syria and attacking them with chemical weapons in Iraq, where they now have an autonomous region in the north that is recognized by the Iraqi constitution.
--With assistance from Niclas Rolander and Ott Ummelas.
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