Turkey’s cabinet announced July 29 that the United States and coalition members targeting the Islamic State (ISIS) would be permitted to fly combat missions from Incirlik air base in south Turkey. This U.S.-Turkish facility is well positioned near the Syrian front, and offers the coalition greater tactical flexibility. It could certainly help in the effort, as President Barack Obama describes it, “to degrade and ultimately destroy” ISIS. But working with Turkey, particularly at Incirlik, comes at a price.

The story of Incirlik begins with the Cold War, when the United States sought a base close to Soviet territory to stage and recover bombers if war erupted between the two superpowers. Turkey’s unique geographic location allowed U.S. forces excellent access to Soviet territory from the south, as well as coverage of the Eastern Mediterranean, Southern and Eastern Europe, and the Middle East.

In 1951, the United States began building an airfield outside the southern city of Adana. In exchange for establishing a U.S. base in its territory, Turkey was granted NATO membership and a bilateral mutual security agreement with the United States in 1952. Turkey and the United States signed a Status of Forces Agreement (SOFA) in 1954, paving the way for the Turkish Air Force and the United States to ink an agreement to share the base. Starting in 1957, the United States began using the base for U-2 reconnaissance flights over the Soviet Union and deployments of fighter squadrons.

In 1958, the U.S. military used the base when Egypt and Syria threatened to overthrow Lebanon’s pro-western president, Camille Chamoun. The U.S. Air Force aircraft flew show-of-force missions, reconnaissance, and leaflet drops from Incirlik. However, the Lebanon operation was undertaken without Turkish permission, using a loophole in the existing SOFA. In 1969, Turkey took steps to restrict Washington’s use of the base through the Defense Cooperation Agreement (DCA), which confined the base’s use to NATO missions rather than American interests.

After the Turkish invasion of Cyprus in 1974, tensions increased when the United States imposed an arms embargo on Turkey. The Turkish cabinet responded by revoking the 1969 DCA, suspending American military operations in the country, allowing only NATO operations at Incirlik. In 1978, the United States lifted the embargo and signed another agreement with Turkey: the 1980 Defense and Economic Cooperation Agreement (DECA), which remains in effect today.

The DECA specifies that American aircraft are “authorized to be stationed at Incirlik installation in support of NATO defense plans.” The agreement does not permit the United States to use the base for its own interests and allows the Turkish government to determine whether the United States can use the base outside NATO missions. Turkey can also cancel U.S. access to Incirlik with three days’ notice.

Given these constraints, it should come as no surprise that the United States’ use of Incirlik has since been limited. During the first Gulf War, Turkey granted the United States permission to launch strikes inside Iraq, though Turkey did not directly participate in the conflict. After the war, the base supported NATO’s Operation Provide Comfort in 1991, and then Operation Northern Watch in 1997.

The 2003 Iraq war revealed tensions between Ankara and Washington. Because the U.S.-led war did not receive U.N. or NATO backing, Turkey barred U.S. combat operations from Incirlik. It also denied the U.S.-led coalition from opening a northern front through Turkey, prolonging the initial invasion and allowing remnants of the regime to slip away. The Turkish government did, however, give the United States permission to use the base for logistical operations to move men and equipment in and out of Iraq. By 2008, 74 percent of the cargo being transferred to Iraq traveled through Incirlik. Had the United States been forced to rely on alternative routes, it would have added $160 million per year to American military spending on the operations in Iraq.

When the campaign against the Islamic State began in 2014, the United States pressed Turkey to open Incirlik to the U.S. military because of its close proximity to territory controlled by the terror group. Turkey hadauthorized four unarmed drones as well as logistics and humanitarian missions to be flown from Incirlik, but despite reports that armed Predators had been authorized in March, it was not until earlier this month that a drone carrying weapons had been permitted to launch. This has severely limited operations into Syria and, to a lesser degree, Iraq since the drones have had to fly from Kuwait to ISIS territory, where intelligence has been hard to glean. The distance has put a high demand on the already stressed drone fleet, resulting in fewer airstrikes.

With the opening of Incirlik to U.S. forces, the shortened distance between eastern Turkey and ISIS-held territory should allow strike aircraft to spend more time over targeted areas and greatly reduce fuel and maintenance costs. It would allow coalition drones to linger longer over Syria if more were deployed from Incirlik rather than Kuwait, thus increasing the amount of intelligence gathered. More importantly, it could also allow for an increased tempo of airstrikes.

If permitted, Incirlik could also provide the United States much needed ability to deploy combat search and rescue (CSAR) teams closer to ISIS territory. From bases in Turkey, CSAR teams flying in tilt-rotor V-22 Ospreys can reach deep into Syria, including to ISIS’s capital, Raqqa, in under an hour, raising the chances of successful hostage and pilot recovery. In the case of the Jordanian pilot downed in December 2014, U.S. Marines based in Kuwait were dispatched to rescue the pilot but failed to reach him in time. The incident lead to the subsequent suspension of operations by the UAE because the Emiratis believed American CSAR assets where not based close enough to Syria.

Yet, despite all of the upside, working with Turkey comes at a cost. The decision to allow Americans to fight from Turkish territory after more than a year of stalling came only after a brutal suicide bombing by a Kurdish jihadist. That attack prompted Ankara to call for action against ISIS, but it also targeted the PKK, thereby suspending peace talks that had been in the works with the Kurdish terror group since late 2012.

Critics of the Turkish government say that ISIS is not the real target. They say that Turkey is really only interested in settling scores with its longtime nemesis, the PKK, and obstructing the advance of the Kurdish People’s Protection Units (YPG) against ISIS on its Syrian border. The YPG are closely affiliated with the PKK, yet they have acted as one of America’s best ally on the ground in Syria, helping to coordinate airstrikes and reversing ISIS’s momentum in northern Syria.

Whether Ankara has ulterior motives is still unclear, but when it has come to fighting the jihadists in Syria, Turkey’s Islamist government has been playing a double game. Turkey’s lax border policies, which were designed to help precipitate the downfall of Syrian dictator Bashar al-Assad, have instead served to benefit many of the jihadi factions now fighting in Syria.

Turkish authorities have not only turned a blind eye to the traffic along the 565-mile border, they have been accused of actively assisting fighters to cross the border. Multiple reports suggest that extremist financiers (mainly from Gulf countries such as Qatar and Kuwait) have been camped out in hotels along the southeastern Turkish frontier, where they have been meeting with jihadist groups since 2012. Meanwhile, the oil fields ISIS conquered have become a significant source of revenue with Turkey serving as the market for the oil. According to Turkey’s main opposition party, $800 million worth of oil from ISIS-occupied regions may have been sold in Turkey in 2014.

Several reports even suggest that Turkey has supplied weapons to jihadi groups operating along the Turkish border, including Jabhat al-Nusra and ISIS. Since 2013, accusations have come from both former Turkish government officials and current opposition parties. The most jarring headlines appeared on January 1, 2014, after the Turkish gendarmerie stopped a suspicious truck headed to Syria in Turkey’s Hatay province. They found weapons and ammunition that allegedly belong to Turkey’s intelligence agency. About two weeks later, on January 19, soldiers stopped and searched another group of trucks in Adana, also carrying weapons that linked to the intelligence agency. Testimonies by two Turkish truck drivers from the Adana case pointed to direct Turkish government involvement. The likely beneficiary was Ahrar al-Sham, the Salafist group with close ties to al-Qaeda.

The Obama administration still insists that Turkey is a solid U.S. partner. In February 2015, for example, Ankara agreed to host training for 5,000-10,000 moderate Syrian rebels. However, the program has been plagued with repeated delays because of disagreements between the United States and Turkey over whether the rebels would target ISIS or the Assad regime. Ankara has even obstructed efforts to combat ISIS. As fighting raged in the Syrian border town of Kobani in October 2014, Turkey protested U.S. efforts to resupply YPG forces battling the terror group, even as its own army sat idly, watching the battle from across the border.

Turkey’s recent reluctance to fight ISIS, and it troubling track record of allowing ISIS to operate on its border, raises troubling questions about Ankara’s commitment to the fight. Moreover, Turkey’s historical reluctance to allow U.S. operations to fully benefit from Incirlik over the years should cast further doubt on the longevity of the new arrangement.

Traditionally, the United States retains military installations in countries where there are common values and interests. The United States may need to utilize Incirlik for the immediate mission, but once operations against ISIS draw down, the American military should consider a permanent alternative.

Jonathan Schanzer is vice president for research at Foundation for Defense of Democracies, where Patrick Megahan is a research analyst for military affairs and manages MilitaryEdge.org.

This article originally appeared in The National Interest.