Abdullah Ö calan actively led the Kurdish liberation struggle as the head of the PKK from its foundation in 1978 until his abduction on February 15, 1999. He is still regarded as a leading strategist and the most important political representative of the Kurdish freedom movement. Under isolation conditions at Imral Island Prison, Ö calan authored more than ten books that revolutionized Kurdish politics. Several times he initiated unilateral cease-fires of the guerrilla and presented constructive proposals for a political solution to the Kurdish issue. For several years, Turkish state authorities led a "dialogue" with Ö calan. Ever since the government broke off the talks in April 2015, he has been held in total isolation at Imral Island Prison, with no contact whatsoever with the outside world.