THE BOYS' BRIGADE

At WSJ, "Kurdish Troops Fighting Islamic State in Syria Say Turkish Forces Shelled Them":

Kurdish fighters who are allied with Washington accused Turkey of shelling their positions in Syria, a sign of the difficulties Ankara and the U.S. face as they boost cooperation to fight Islamic State militants.

Monday’s accusation came from the Kurds’ People’s Defense Units, a Syrian group that has emerged as the most effective U.S. partner in the fight against the Islamist extremists. Its role has complicated matters for Turkey, which is worried about growing Kurdish influence along its border with Syria and an emboldened Kurdish minority seeking more autonomy at home.

Turkey said its forces were fired upon from unidentified sources across the Syrian border and that it responded with artillery. It said it was investigating claims that several Kurdish fighters were wounded but that the Syrian-Kurdish defense units, known as the YPG, “do not fall within the scope of Turkey’s war on terror.”

U.S. officials said Monday that they weren’t aware of any border attack but stood by Turkey’s right to defend itself.

The episode underscores the fragility of an agreement between the U.S. and Turkey for American jets to use Turkey’s air bases to strike Islamic State positions and help create a 60-mile-long buffer zone in Syria for moderate rebels fighting President Bashar al-Assad. The details have yet to be worked out. Meanwhile, Turkey itself has also begun launching airstrikes against Islamic State targets.

Turkey’s new more aggressive stance is sure to emerge on Tuesday in Brussels at a North Atlantic Treaty Organization meeting, which Ankara called to discuss its security threats, including recent bouts of violence that have killed scores of Turkish civilians and security officials.

But as the U.S. tries to compartmentalize long-standing political differences between Turkey and Syrian Kurds, the two sides appear to have come into confrontation.

The YPG, which controls a swath of territory in northeast Syria along Turkey’s border, accused the Turkish army of hitting positions in the area with tank fire on Friday and injuring several villagers and four allied fighters from the Western-backed moderate Free Syrian Army rebel group. The Kurdish group said the Turkish military shelled the same village on Sunday and fired on a vehicle nearby.

“Instead of targeting Islamic State terrorists’ occupied positions, Turkish forces attack our defenders’ positions,” the YPG said. “We are telling the Turkish army to stop shooting at our fighters and their positions.”

Meanwhile, Ankara is also getting dragged deeper into a major regional conflict that it had sought to avoid, adding an additional layer of complexity to the patchwork of alliances—including Sunni rebel groups, jihadists, Kurdish militias and forces loyal to Mr. Assad—which are vying for influence along Turkey’s southern borderlands...

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