How Trump’s moves in Syria threaten U.S.-Turkey alliance

After Turkish President Recep Tayyip Erdogan won a narrow victory last month in a contested referendum that gave him sweeping new powers, President Donald Trump was the only Western leader who called to congratulate him. Most other leaders steered clear of endorsing a power grab by the increasingly autocratic Erdogan.

The call was one sign of a budding friendship between Trump and Erdogan, with the two leaders issuing supportive statements after several phone calls since Trump won the U.S. presidential election in November.

But the honeymoon didn't last long. On May 16, Trump and Erdogan will meet for the first time at the White House. The talks have been overshadowed by tension over Trump's decision to arm Kurdish fighters from the People's Protection Units (known as the YPG) in Syria, instead of relying on Turkey and its Syrian proxies to fight Islamic State.

Turkish leaders view the YPG and other Syrian Kurdish groups as allies of the Kurdistan Workers' Party, known as the PKK, which has waged an insurgency against the Turkish government since the 1980s. Turkey also fears that the YPG and other groups will create an autonomous Kurdish region in northern Syria, which would inspire Kurdish separatists inside Turkey.

But the White House views the YPG as a key partner in the fight against Islamic State, and separate from the PKK. On May 9, the Trump administration approved a Pentagon plan to provide heavy weapons to Kurdish YPG rebels fighting to expel Islamic State from Raqqa, capital of its self-proclaimed caliphate. The decision has pitted the two main U.S. allies in the Syrian war against each other. And it raises a crucial question: Is Turkey willing to seriously disrupt the U.S.-led war against Islamic State to undermine Washington's support for the Kurds?

Turkey could disrupt the Pentagon's battle against the jihadists in several ways. Erdogan's government could limit access to the Incirlik air base, which is an important hub for U.S. fighter jets that carry out strikes against Islamic State targets in both Syria and Iraq. One Turkish newspaper recently called on the government to expel all 2,500 U.S. troops assigned to Incirlik, in retaliation for Washington's decision to arm the Kurds. But it's unlikely that Erdogan would entirely ban U.S. forces from Incirlik, since Turkey benefits from intelligence sharing at the base, including feeds from U.S. drones operating in Syria and Iraq.

Turkey already risked disrupting the war against Islamic State when it targeted the YPG last month. On April 25, Turkish warplanes bombed Kurdish militia bases in Syria and Iraq, killing at least 20 fighters. After the attacks, YPG fighters and Turkish troops exchanged artillery fire along the Syrian-Turkish border for several days. The Pentagon then moved U.S. troops and armored vehicles along parts of the Syrian border to act as a buffer between Kurdish and Turkish forces.

Erdogan and his military have been wary of Kurdish gains in Syria for several years, but Ankara became especially worried last year after the YPG, with U.S. training and logistical help, captured significant territory from Islamic State. Erdogan urged then-U.S. President Barack Obama to withhold support from Kurdish fighters and instead provide weapons and resources to other Syrian rebel factions backed by Turkey. But Obama and the Pentagon insisted that the YPG was the most effective fighting force against Islamic State. To counter U.S. support for the YPG, Turkey sent several hundred of its special forces into Syria, and began carrying out air strikes to help its allies consolidate control of territory near the Turkish-Syrian border.

After the U.S. election, Erdogan hoped that Trump would be more sympathetic to Turkey's concerns than Obama. But Erdogan lost his main supporter in Trump's inner circle when Michael Flynn, the national security adviser, was forced to resign after only 24 days in office. (After his ouster, Flynn admitted that, while he was advising Trump's presidential campaign, he had earned more than $500,000 as a lobbyist for a Turkish businessman linked to Erdogan.)

Once in office, Trump and his advisers continued U.S. support for the Syrian Democratic Forces (SDF), a coalition of Kurdish, Sunni Arab and Christian rebel groups that is anchored by the YPG. In the waning days of the Obama administration, the SDF had launched a ground offensive of about 30,000 fighters, backed by intensive U.S. air strikes, to oust Islamic State from Raqqa. After six months of fighting, the rebels are now within miles of the city's outskirts.

Under Trump's latest directive, the Pentagon will provide heavier weaponry to the SDF and YPG specifically, including mortars, anti-tank weapons, heavy machine guns and armored vehicles. The new arms will help the rebels withstand intense urban and guerrilla warfare they expect to encounter from several thousand Islamic State fighters holed up in Raqqa.

During his White House visit, Erdogan had planned to lobby Trump to drop his administration's support of the YPG, and instead back Turkey's favored Syrian rebels to capture Raqqa. But after Trump adopted the Pentagon's plan to continue arming the YPG, Erdogan might go home empty-handed.

If he's rebuffed by Trump, Erdogan could step up his campaign of air strikes and other incursions against Syrian Kurds. If the conflict intensifies between Turkey and the Kurds, the YPG could be forced to divert some of its fighters away from the Raqqa battle to protect a Kurdish enclave in northern Syria called Rojava. Some Kurdish leaders are also threatening to withdraw from the campaign against Islamic State, unless Washington protects them from further attacks by Turkey.

Erdogan hinted that his military would carry out more air strikes against YPG bases in Syria. "We can come unexpectedly in the night…" he said on April 30. "We are not going to tip off the terror groups and the Turkish Armed Forces could come at any moment."

Ironically, by trying to weaken the Kurds in Syria, Erdogan could prolong the battle for Raqqa and ultimately help Islamic State. And that would be a defeat for Trump, who has framed the battle against the jihadists as his highest priority.