An ISIS fighter walks near a black flag belonging to the Islamic State as a Turkish army vehicle takes position near the Syrian town of Kobani, as pictured from the Turkish-Syrian border near the southeastern town of Suruc, Sanliurfa province, October 7, 2014. REUTERS/Umit Bektas A US-led raid on the compound housing the Islamic State's "chief financial officer" produced evidence that Turkish officials directly dealt with ranking ISIS members, Martin Chulov of the Guardian reported recently.

The officer killed in the raid, Islamic State official Abu Sayyaf, was responsible for directing the terror army's oil and gas operations in Syria. The Islamic State (aka ISIS, ISIL, or Daesh) earns up to $10 million a month selling oil on black markets.

Documents and flash drives seized during the Sayyaf raid reportedly revealed links "so clear" and "undeniable" between Turkey and ISIS "that they could end up having profound policy implications for the relationship between us and Ankara," senior Western official familiar with the captured intelligence told the Guardian.

NATO member Turkey has long been accused by experts, Kurds, and even Joe Biden of enabling ISIS by turning a blind eye to the vast smuggling networks of weapons and fighters during the ongoing Syrian war.

The move by the ruling AKP party was apparently part of ongoing attempts to trigger the downfall of Syrian President Bashar Assad's regime.

Ankara officially ended its loose border policy last year, but not before its southern frontier became a transit point for cheap oil, weapons, foreign fighters, and pillaged antiquities.

In November, a former ISIS member told Newsweek that the group was essentially given free rein by Turkey's army.

"ISIS commanders told us to fear nothing at all because there was full cooperation with the Turks," the fighter said. "ISIS saw the Turkish army as its ally especially when it came to attacking the Kurds in Syria."

But as the alleged arrangements progressed, Turkey allowed the group to establish a major presence within the country — and created a huge problem for itself.

"The longer this has persisted, the more difficult it has become for the Turks to crack down [on ISIS] because there is the risk of a counter strike, of blowback," Jonathan Schanzer, a former counterterrorism analyst for the US Treasury Department, explained to Business Insider in November.

"You have a lot of people now that are invested in the business of extremism in Turkey," Schanzer added. "If you start to challenge that, it raises significant questions of whether" the militants, their benefactors, and other war profiteers would tolerate the crackdown."

An armed man, believed to be an ISIS militant, seen near the northern Syrian town of Tal Abyad as he is pictured from the Turkish border town of Akcakale, southeastern Sanliurfa province, January 29, 2015. REUTERS/Osman Orsal

A Western diplomat, speaking to The Wall Street Journal in February, expressed a similar sentiment: "Turkey is trapped now — it created a monster and doesn’t know how to deal with it."

Ankara had begun to address the problem in earnest — arresting 500 suspected extremists over the past six months as they crossed the border and raiding the homes of others — when an ISIS-affiliated suicide bomber killed 32 activists in Turkey's southeast on July 20.

Turks subsequently took to the streets to protest the government policies they felt had enabled the attack.

Demonstrators burn tires to block a street during protests against Monday's bomb attack in Suruc, in the Kurdish dominated southeastern city of Diyarbakir, Turkey, July 21, 2015. REUTERS/Sertac Kayar Amidst protesters' chants of "Murderous ISIL, collaborator AKP," Erdogan finally agreed last Thursday to enter the US-led campaign against ISIS, sending fighter jets into Syria and granting the US strategic use of a key airbase in the southeast to launch airstrikes.

At the same time, Turkey began bombing Kurdish PKK shelters and storage facilities in northern Iraq, the AP reported, indicating that the AKP still sees Kurdish advances as a major — if not the biggest — threat, despite the Kurds' battlefield successes against ISIS in northern Syria.

“This isn’t an overhaul of their thinking," a Western official in Ankara told the Guardian. "It’s more a reaction to what they’ve been confronted with by the Americans and others. There is at least a recognition now that ISIS isn’t leverage against Assad. They have to be dealt with.”