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Although ISIS has not claimed responsibility, officials say the bombings bear ISIS' signature

The U.S. has frequently implored Turkey to up its efforts against the terror group

Washington CNN  — 

American officials have long wanted Turkey to be as committed to the fight against ISIS as is the U.S. With the attack on Istanbul’s Ataturk Airport Tuesday, ISIS might have helped make the case for them.

While Turkey has been the victim of ISIS attacks in the past – including one that killed 95 civilians at an Ankara peace rally in October – the U.S. and Turkey have not always seen eye-to-eye on the counter-ISIS campaign.

The U.S. has frequently implored Turkey to up its efforts against the terror group, also know as ISIL and Daesh.

“I would like Turkey to do more,” Secretary of Defense Ash Carter said in January at the Davos Economic Forum. “I think the Turks can do more to fight ISIL. They’re helping us fight ISIL by, for example, hosting our aircraft in Turkey. I’m grateful for that. But I think they can do more.”

Turkey sits at the crossroads between ISIS’ haven in Syria and the West, and the Muslim-majority NATO member state is key for everything from stopping the flow of foreign fighters to allowing use of its strategically vital Incerlik air base.

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But to date, “Turkey has been a somewhat ambivalent warrior against ISIS,” James Jeffrey, former U.S. ambassador to Turkey, told CNN’s Brianna Keilar Thursday.

Though ISIS has not claimed responsibility for Tuesday’s suicide bombings, which left at least 43 dead, many security officials have said the attack bears ISIS’ signature.

Turkish officials themselves have said they’ve uncovered evidence that the attackers traveled from ISIS’ de facto capital in Raqqa, Syria.

The devastating nature of Tuesday’s attack, targeted at the heart of Turkey’s crucial tourism industry and including a number of international victims, leads some in Washington to think that the Turks might finally fully embrace U.S. efforts to combat ISIS, including American reliance on Kurdish fighters that Turkey has opposed.

Jeffrey said that until now Turkish ambivalence has been caused by the fact that Turkey has prioritized other interests in Syria – primarily their long-running conflict with the Kurds, who have been strong partners to the U.S. in the fight against ISIS to the consternation of Ankara.

The primary U.S.-backed local force that has made significant gains against ISIS in Syria are the Syrian Democratic Forces, a coalition group comprised in part of the highly effective Syrian-Kurdish YPG.

Turkey sees the YPG as a branch of the PKK, a group of Kurdish rebels that for decades has carried out bloody terror attacks in Turkey in a bid for an independent state for Turkey’s Kurdish minority. The U.S. also considers the PKK a terror organization, but makes a distinction between it and the YPG.

And while the U.S. has called for Syrian President Bashar al-Assad to leave power, the Turks are much more committed to seeing him ousted. Longtime regional rivals, Turkey faults Assad for the five-year Syrian civil war that has driven millions of refugees into Turkey, and relations only soured further when the Syrian military downed a Turkish jet in 2012.

The Turks, as Jeffrey put it, “have other fish to fry, including the PKK Kurdish rebels and the Syrian government.”

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The U.S. closeness with the Kurds in Syria and Iraq has also made the Turks uneasy, worrying them about the creation of an independent Kurdistan that could destabilize Turkey.

Turks were outraged in May when U.S. Special Operations Forces were photographed wearing the insignia of the YPG fighters that they were training and advising in Syria, something the Pentagon also deemed a mistake.

State Department spokesman Mark Toner acknowledged the differences of opinion between the U.S. and Turkey Wednesday.

It’s “very clear that we view the PKK as a foreign terrorist organization, and as such, we work with Turkey on combating them,” he said. “But we draw clear delineation between the PKK and the Syrian Kurds.”

The U.S. has also taken issue with the foreign fighters that have traveled across Europe, through Turkey and into Syria, believing more could be done to stamp out the phenomenon.

“The Turks let them in believing they were going to fight Assad,” Bulent Aliriza, director of the Turkey project at the Center for Strategic and International Studies, told CNN.

Aliriza added that the fact that many of these fighters would go on to join ISIS was “an unintended byproduct” of Turkey’s anti-Assad strategy.

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In addition to the thousands of Europeans who transited through Turkey, as of December over 2,000 Turks have traveled to Syria and Iraq to fight. And of those, over 600 have returned to Turkey, according to the Soufan Group, a security consultancy that tracks foreign fighters.

There have, however, been points of cooperation between the U.S. and Turkey in combatting ISIS.

“I also don’t want to underplay or under-emphasize Turkey’s role in the coalition,” Toner said. “I think we’ve made real progress in the last – certainly in the last year – working with Turkey in order to bring more pressure to bear on Daesh.”

Significantly, Turkey granted the U.S. the ability to use the airbase at Incirlik for its air campaign against ISIS. Just about 60 miles from the Syrian border, Incirlik’s proximity to ISIS territory makes it a critical asset.

Still, the U.S. had to lobby Turkey for months for the right to use the base for this purpose, only getting access in July 2015.

“Turkey and the U.S. were not on the same page,” Aliriza said.

While Turkey has conducted some air and artillery strikes against ISIS fighters along the Syria-Turkish border, the bulk of its strikes have been directed against Kurdish groups.

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But Jeffrey told CNN that Turkey is now likely to ramp up its role in the anti-ISIS fight.

“This will pull Turkey into the war against ISIS more and that’s a good thing,” he said.

A more involved Turkey could have a major impact on the counter-ISIS campaign, as Turkey possesses the second-largest armed forces in NATO.

Aliriza noted that Turkey is likely to crack down on internal ISIS sympathizers and continue efforts to secure the border with Syria in the wake of Tuesday’s attack. Ankara has already started using artillery to respond to ISIS in Syria.

He also sees the so-called Manbij Pocket, the 60-mile ISIS-controlled swath on the Syrian-Turkish border, as a potential target for a Turkish anti-ISIS push.

But he added that Turkey will continue to see Assad and the Kurds, despite being enemies of ISIS, as major threats.

He cautioned against “optimistic sentiments being expressed in Washington” of an increased Turkish role in Syria taking on ISIS.