The Turkish army carried out strikes against Kurdish militants in Iraq’s Sinjar region and northeastern Syria on Tuesday.

The strikes in Iraq targeted the outlawed Kurdistan Workers Party (PKK) and those in Syria targeted the YPG – a key component of the Syrian Democratic Forces (SDF), which are backed by the United States and have been closing in on the ISIS-held city of Raqqa.

The Turkish military said the aim of the strikes was to prevent the PKK from sending weapons and explosives for attacks inside Turkey.

“To destroy these terror hubs which threaten the security, unity and integrity of our country and our nation and as part of our rights based on international law, air strikes have been carried out … and terrorist targets have been struck with success,” the Turkish army said in a statement.

The air bombardment was carried out around 02.00 a.m., it added.

A Turkish security official, speaking on condition of anonymity in line with Turkish government protocol, said the airstrikes are believed to have killed around 200 Kurdish militants, including some senior commanders. The claim could not be independently confirmed.

A Syrian Kurdish militia force said the strikes hit a media center, a local radio station, a communication headquarters and some military posts, killing an undetermined number of fighters in Syria’s northeastern Hassakeh province.

“This treacherous attack has led to the death and wounding of a number of our comrades,” read a statement from the YPG general command.

The British-based Syrian Observatory for Human Rights, a monitoring group which tracks violence using sources on the ground, said three YPG fighters had been killed in the strikes.

Turkey’s warplanes have regularly bombed the mountainous border area between Iraq and Turkey where PKK militants are based since a ceasefire broke down in July 2015, but it is the first time it has targeted its affiliate in the Sinjar region.

Turkish President Recep Tayyip Erdogan has said he will not allow Sinjar, around 115 km (70 miles) from the Turkish border, to become a “new Qandil”, referring to the PKK stronghold near the borders of Turkey, Iraq and Iran.

General Seme Bosali, a senior Kurdish military commander in Sinjar, said the air strike had killed five Kurdish peshmerga fighters. It appeared to be a mistake, he said, as the peshmerga forces are not hostile to Turkey.

Designated a terrorist group by Turkey, the United States and the European Union, the PKK has waged a three-decade insurgency against the Turkish state for Kurdish autonomy. More than 40,000 people have been killed in the conflict.

In November, the Turkish army deployed tanks and armored vehicles to the border town of Silopi, around the time Iraqi forces supported by the United States launched an operation to drive ISIS from the northern Iraqi city of Mosul.

The government at the time said the move was to fortify Turkey’s defenses against developments across its borders.