Kurdish militants who have waged a 40-year insurgency in Turkey declared a ceasefire on Saturday in what could mark a significant boost to President Recep Tayyip Erdogan's government, two days after their imprisoned leader called for the group to disarm.

The group, the P.K.K., made its declaration days after its long-imprisoned leader urged the movement to disarm and disband, but there are still many questions about the prospects for ending 40 years of deadly conflict.