For years, Turkey has fought an off-and-on war with the Kurdistan Workers Party, or PKK. The guerrilla group–based along the Iraqi-Turkish border–carries out raids,...

For years, Turkey has fought an off-and-on war with the Kurdistan Workers Party, or PKK. The guerrilla group–based along the Iraqi-Turkish border–carries out raids, and in response, Turkey launches air strikes, artillery bombardments and even the occasional ground invasion.

The Kurdish guerrillas use the mountainous border region as a sanctuary–and they’re very, very good at fighting in it.

The latest escalation has Turkish warplanes bombing targets in both southeastern Turkey and northern Iraq. On Aug. 11, Turkish warplanes bombed 17 targets. This latest escalation is the first since August 2011, when PKK attacks resulted in Turkey striking 132 PKK targets.

The new Turkish campaign, however, comes at a time when the PKK remains a formidable opponent of Islamic State. Making matters more complicated, the People’s Protection Units–a PKK affiliate–is the only group in Syria the United States has had much luck coordinating with.

In Iraq’s Sinjar region, the PKK came to the help of terrorized Iraqi Christians and Yezidis. Now the guerrillas are calling for the creation of a Yezidi statelet–a clear and direct challenge to the Kurdistan Regional Government’s sovereignty and authority.

Iraqi Kurdish president Massoud Barzani criticized the Turkish attacks. “We condemn the bombing, which led to the martyrdom of the citizens of the Kurdish region, and we call on Turkey not to repeat the bombing of civilians,” Barzani said in a statement.

But he also called on the PKK to vacate Kurdish territory in Iraq. Iraq’s government in Baghdad criticized Turkey for violating Iraq’s sovereignty, but stressed that Turkey should coordinate with the Iraqi government during any campaign.

These contorted and confusing political alliances are not new. In the mid-1990s, Barzani’s Kurdistan Democratic Party and Jalal Talabani’s Patriotic Union of Kurdistan fought a bitter civil war over who would control the Iraqi Kurdish enclave.

While Talabani reached out to Tehran for support, Barzani briefly coordinated with Saddam Hussein. The Iraqi dictator sent at least 30,000 Iraqi troops into Iraqi Kurdistan, forcing the PUK from Erbil and allowing the KDP take over before withdrawing.

In 1997, Turkey launched a large scale operation to deny the PKK from using Iraqi Kurdistan as a sanctuary. Ankara had long accused Tehran of supporting the PKK against the Turkish state.

Given that the PUK was closer to Tehran, Turkey in turn sought to reinforce Barzani–reasoning that he could serve as an effective bulwark against the PKK.

Then, like now, Barzani insisted that the PKK should withdraw its forces from Iraqi Kurdistan. Turkey sent in at least 25,000 soldiers–some estimates go as high as 50,000–into the region as part of Operation Hammer, which lasted from mid-May until early July of that year.

The PKK didn’t stand down without a fight. The guerrillas clashed with Pershmerga fighters loyal to Barzani, resulting in firefights on the streets of Erbil. Thousands of people fled the border regions, today marked by the ruins of hundreds of abandoned villages. The rebels never left.

Echoes of 1997 are audible today. However, Iraq is now a very different place and the KRG has ruled out expelling the PKK by force. “I think if there is a clash it will be after ISIS is gone and it will be quiet and nasty, more of a police and intelligence campaign than a straight-up gunfight,” Michael Knights, an Iraqi specialist with the Washington Institute, told War Is Boring.

In short–the PKK’s presence has raised substantial ire from the KRG, which wants the guerrillas out. The Kurdish government won’t fight them, but is also clearly acquiescing to the Turkish intervention like it did in 1997. But as history demonstrated, it will be no easy task to remove the guerrillas from the mountains.