A member of the Patriotic Revolutionary Youth Movement (YDG-H), a division of the PKK, stands guard in the south-eastern Turkish city of Nusaybin on February 25, 2016. Getty Images
A group of PKK soldiers walk near their base camp high in the mountains of northern Iraq on June 1, 2004. Reuters
Kurdistan Workers' Party (PKK) leader Abdullah Ocalan greets women soldiers at the Mahsun Korkmaz Academy military training camp in Lebanon on June, 18, 1988. Getty Images
Peshmerga and Turkish soldiers prepare to storm a hill on October 23, 1992, near a stronghold held by the PKK in Hakurk Valley. AFP
Abdullah Ocalan was abducted in Nairobi in 1999 by the Turkish National Intelligence Agency (MIT), with assistance from the US, and taken to Turkey. Reuters
Turkish riot police detain a Kurdish protester following a demonstration in central Istanbul on April 2, 2006. Reuters
A man holds a sign demanding freedom for imprisoned Kurdish leader Abdullah Ocalan at a protest of mostly Kurdish demonstrators on November 4, 2007, in Berlin, Germany. Getty Images
Turkish army commandos on patrol near the Iraq border on October 27, 2007, in the Uludere district of Sirnak province, south-eastern Turkey. Getty Images
A Turkish helicopter flies over the Cudi Mountains during an attack on an outlawed PKK camp October 30, 2007, in Sirnak province, near the Iraq border. AFP
A ruined bridge lies in northern Iraq's Kurdistan region during fighting between Turkish forces and PKK fighters on February 24, 2008. AFP
Turkish soldiers stand guard as smokes rises from a bus that was attacked by members of the PKK on September 18, 2012, in Bingol. AFP
A member of the PKK inspects a crater reportedly caused by an air strike by Turkish warplanes on July 29, 2015, in the Qandil Mountains in northern Iraq. AFP
Locals assess the damage following clashes between Turkish forces and PKK militants in the Kurdish-majority city of Cizre, in south-eastern Turkey, on September 12, 2015. AFP
People return to their homes in Dargecit after a curfew imposed by the Turkish government was lifted on December 30, 2015, in Mardin province. AFP
Children look out from a window of a bullet-scarred house in the Kurdish town of Silopi in south-eastern Turkey, near the border with Iraq, on January 19, 2016. AFP
A member of the Patriotic Revolutionary Youth Movement (YDG-H), a division of the PKK, stands guard in the south-eastern Turkish city of Nusaybin on February 25, 2016. Getty Images
A group of PKK soldiers walk near their base camp high in the mountains of northern Iraq on June 1, 2004. Reuters
Kurdistan Workers' Party (PKK) leader Abdullah Ocalan greets women soldiers at the Mahsun Korkmaz Academy military training camp in Lebanon on June, 18, 1988. Getty Images
Peshmerga and Turkish soldiers prepare to storm a hill on October 23, 1992, near a stronghold held by the PKK in Hakurk Valley. AFP
Abdullah Ocalan was abducted in Nairobi in 1999 by the Turkish National Intelligence Agency (MIT), with assistance from the US, and taken to Turkey. Reuters
Turkish riot police detain a Kurdish protester following a demonstration in central Istanbul on April 2, 2006. Reuters
A man holds a sign demanding freedom for imprisoned Kurdish leader Abdullah Ocalan at a protest of mostly Kurdish demonstrators on November 4, 2007, in Berlin, Germany. Getty Images
Turkish army commandos on patrol near the Iraq border on October 27, 2007, in the Uludere district of Sirnak province, south-eastern Turkey. Getty Images
A Turkish helicopter flies over the Cudi Mountains during an attack on an outlawed PKK camp October 30, 2007, in Sirnak province, near the Iraq border. AFP
A ruined bridge lies in northern Iraq's Kurdistan region during fighting between Turkish forces and PKK fighters on February 24, 2008. AFP
Turkish soldiers stand guard as smokes rises from a bus that was attacked by members of the PKK on September 18, 2012, in Bingol. AFP
A member of the PKK inspects a crater reportedly caused by an air strike by Turkish warplanes on July 29, 2015, in the Qandil Mountains in northern Iraq. AFP
Locals assess the damage following clashes between Turkish forces and PKK militants in the Kurdish-majority city of Cizre, in south-eastern Turkey, on September 12, 2015. AFP
People return to their homes in Dargecit after a curfew imposed by the Turkish government was lifted on December 30, 2015, in Mardin province. AFP
Children look out from a window of a bullet-scarred house in the Kurdish town of Silopi in south-eastern Turkey, near the border with Iraq, on January 19, 2016. AFP
A member of the Patriotic Revolutionary Youth Movement (YDG-H), a division of the PKK, stands guard in the south-eastern Turkish city of Nusaybin on February 25, 2016. Getty Images