ANKARA, Turkey (AP) — Turkey on Thursday blamed Kurdish militants at home and in neighboring Syria for a deadly bombing in Ankara and it stepped up pressure on the U.S. to sever ties with the Syrian Kurdish militia that has been a key force against the Islamic State group in the complex Syrian conflict.
The blast at rush hour Wednesday killed 28 people and wounded dozens more in a car bombing that targeted buses of military personnel. Ankara's second bombing in four months came as Turkey grappled with an array of serious issues, including renewed fighting with Kurdish rebels, threats from Islamic State militants and the Syria refugee crisis.
Prime Minister Ahmet Davutoglu said a Syrian national with links to Syrian Kurdish militias carried out the attack in concert with Turkey's own outlawed Kurdish rebel group, the Kurdistan Workers' Party, or PKK, which has waged a 30-year insurgency. He also blamed the government of President Bashar Assad for allegedly supporting the Syrian Kurdish militia.
Turkish leaders vowed to retaliate for the Ankara attack, and the military said its warplanes conducted cross-border raids within hours against PKK positions in the Haftanin region of northern Iraq, striking about 60-70 rebels, including senior leaders. The report could not be independently verified.
Turkey had been pressing the U.S. in recent weeks to cut off its support to the Kurdish Syrian militias that Ankara regards as terrorists because of their affiliation with the PKK. President Recep Tayyip Erdogan urged Washington to choose between Turkey and the Syrian Kurdish group as its partner.
The U.S. already lists the PKK as a terrorist group. But in the complicated tangle of friends and foes in the Middle East, Washington relies heavily on the Syrian Democratic Union Party, or PYD, and its military wing, the People's Protection Units, or YPG, in fighting extremists from the Islamic State group.
The U.S. has rejected Turkish pressure to brand those Kurdish groups as terrorists. Turkey also wants the United States to stop providing weapons to the Syrian Kurdish militias, arguing that the arms end up with the PKK.
Turkish leaders pushed that effort further Thursday.
"Those who directly or indirectly back an organization that is the enemy of Turkey risk losing the title of being a friend of Turkey," Davutoglu said in an apparent reference to Washington. "It is out of the question for us to excuse a terror organization that threatens the capital of our country."
Erdogan said the bombing would serve to make Turkey's friends "better understand how strong are the links between PYD and YPG in Syria's north with the PKK in Turkey."
The ambassadors of the U.S., Russia, Britain, China and France — the five permanent U.N. Security Council members — were invited separately to Turkey's Foreign Ministry and briefed on the Ankara bombing, a ministry official said. Ambassadors to Germany and the Netherlands, as well as the head of the European Union delegation, also were invited. The official spoke on condition of anonymity because she wasn't authorized to talk publicly on the issue.
Soner Cagaptay, director of the Turkish Research Program at the Washington Institute for Near East Policy, said the attack blamed on the Kurdish militias places the U.S. in a difficult position.
"If Turkey were to launch full-throttle battle against the PYD, this would almost certainly hurt U.S.-Turkish ties, which is exactly what the PKK would want to achieve from the attack in Ankara," Cagaptay said.
"And if Ankara provides convincing evidence that the PYD was behind the attack, Washington will be left between a rock and a hard place to choose either Ankara or PYD as its key ally against the so-called Islamic State in Syria," he said.
An Arab-Kurdish alliance dominated by the YPG has made significant advances against IS and other insurgents in northern Syria near the Turkish border in the past week. On Wednesday, the U.S.-backed group known as the Syria Democratic Forces launched an offensive to try to reach Shaddadeh, a major IS stronghold in Syria's northeastern Hassakeh province, which borders Iraq.
The Britain-based Syrian Observatory for Human Rights, an opposition activist group that monitors the 5-year-old civil war, said the Syria Democratic Forces — which is dominated by YPG fighters — had seized eight villages around the town of Hol in the past 24 hours.
Turkish artillery has been shelling PYD and YPG positions along its border in Syria, apparently concerned by recent gains there by the militias. Any Turkish escalation against the PYD is likely to further strain ties with the U.S.
"It has been determined with certainty that this attack was carried out by members of the separatist terror organization together with a member of the YPG who infiltrated from Syria," Davutoglu said, identifying the Ankara bomber as Salih Neccar.
He was born in 1992 in the mostly Kurdish Syrian town of Amouda, near the Turkish border, Davutoglu said.
At least 14 people have been arrested in the Ankara attack, Erdogan said, adding that the number of detained suspects is likely to increase.
In an interview with The Associated Press, the leader of the main Syrian Kurdish group, Salih Muslim, denied his group was behind the bombing, and he warned Turkey against taking ground action in Syria.
Cemil Bayik, the leader of a Kurdish umbrella organization that includes the PKK, told the pro-Kurdish Firat News agency that he did not know who was behind it. But he suggested that Kurdish militants, angered by Ankara's military operations in southeastern Turkey, may have acted independently.
Erdogan insisted the evidence pointed to the Syrian Kurdish group.
"Despite the fact that their leader says they have nothing to do with this, the information and documents obtained by our Interior Ministry and all our intelligence organizations shows that (the attack) was theirs," Erdogan said.
In new violence in southeastern Turkey, six soldiers were killed after PKK rebels detonated a bomb on a road linking the cities of Diyarbakir and Bingol, the state-run Anadolu Agency reported.
Hundreds of people have been killed in Turkey in renewed fighting following the collapse of the peace process between the government and the Kurds in July. The fighting has displaced tens of thousands in the area as Turkey carried out large-scale military operations against PKK-linked militants.
Turkey also has been struck by several bombings in the last year that were blamed on IS as the government joined efforts led by the U.S. to fight the extremist group in Syria. The deadliest came in October when a peace rally outside Ankara's main train station killed 102 people.
Turkey also has been housing tens of thousands of refugees from the Syrian war, including many who have streamed to the border in recent weeks amid airstrikes and ground fighting in northern Syria near Aleppo.
Associated Press writers Bassem Mroue in Beirut and Jan M. Olsen in Copenhagen, Denmark, contributed to this report.