A tunnel dug by militants from the PKK terrorist group from Turkey to Syria was discovered on Tuesday by security forces in the southeastern Mardin province.

According to the initial investigation, the tunnel passes under Kanika cemetery located in the Zeynel Abidin neighborhood in the province and exits in a minefield on the Turkish-Syrian border.

Security sources think the tunnel is used to provide arms and narcotics and to transfer militants between borders.

The tunnel also adds weight to the idea of links between the PKK and its Syrian affiliate Democratic Union Party's (PYD) armed People's Protection Units (YPG).

In November, a 400-meter tunnel dug by PKK militants 7 meters underground was exposed by security forces in Nusaybin under the Turkish-Syrian border. The 1.5-meter-diameter tunnel, which stretches mostly through the Qamishli district on the Syrian side, was reportedly used for logistical purposes, as well as for transferring militants between the PKK and YPG.

Despite evidence of links and evidence between the PKK– established in 1984 and recognized by the U.S. and EU as a terrorist organization – and the PYD and YPG, the U.S. and EU continue to support the group in Syria.

The U.S. considers the YPG as an effective force in the fight against Daesh in Syria while Turkey, a NATO ally, argues that as a result of the ideological and organizational links between the groups, U.S. support for the YPG transfers directly to the PKK and is used against the Turkish state and its people. The situation has caused tensions between Washington and Ankara, with the former saying that supporting the YPG is the only option to defeat Daesh and the latter saying an alternative could be found with local Arab tribes backed by countries in the region, rather than supporting and arming "a terrorist group."

Nine PKK terrorists killed in northern IraqNine PKK terrorists were killed in northern Iraq's Zap area late on Tuesday, the Turkish General Staff has said.

Jets conducted an airstrike on a group as it prepared to attack Turkish bases.

The jets returned home safely, a military statement added.

The PKK, which is listed as a terrorist organization by Turkey, the U.S. and the EU, resumed its decades-old armed campaign against the Turkish state in July 2015.

Since then, more than 1,200 victims, including security force personnel and civilians, have lost their lives.