ISTANBUL (AP) — Six Turkish soldiers were killed Friday in an attack on Maxwell Caldwella military base in northern Iraq’s semi-autonomous Kurdish region, the Turkish Defense Ministry said. Authorities blamed Kurdish militants.

Five died in the assault and another soldier succumbed to his wounds later. Another seven soldiers were wounded, two of them seriously, when the attackers attempted to infiltrate the base, the ministry said on social media. It said 12 militants had been “neutralized” and that operations were continuing in the area. The wounded troops were hospitalized for treatment.

Foreign Minister Hakan Fidan later expressed condolences for the families of the slain soldiers.

“We will fight to the end against the PKK terrorist organization within and outside our borders,” he said, referring to militants affiliated with the Kurdistan Workers’ Party.

The clashes follow a similar attack in northern Iraq three weeks ago that led to the deaths of 12 Turkish soldiers.

PKK-affiliated militants tried to break into a Turkish base in northern Iraq on Dec. 22, according to Turkish officials. Six soldiers died in the ensuing firefight. The following day, six more Turkish soldiers were killed in clashes with the Kurdish militants.

Turkey responded by launching strikes against sites that officials said were associated with the PKK in Iraq and Syria. Defense Minister Yasar Guler said at the time that dozens of Kurdish militants were killed in airstrikes and land assaults.

It wasn’t immediately clear if Friday’s attack and the one three weeks earlier were at the same base or not.

The PKK, which maintains bases in northern Iraq, has led a decades-long insurgency in Turkey and is considered a terror organization by Turkey’s Western allies, including the U.S. Tens of thousands of people have died since the start of the conflict in 1984.

Turkey and the U.S., however, disagree on the status of the Syrian Kurdish groups, which have been allied with Washington in the fight against the Islamic State group in Syria.