Crowds gathered in Turkey’s capital Ankara on Sunday to mourn the victims of a bombing at a peace rally that killed at least 95 people and injured nearly 300 others.
The Turkish military responded with airstrikes after an attack that could be the bloodiest assault since the collapse of a ceasefire in July.
Turkey's Prime Minister Ahmet Davutoglu said border security would be increased as authorities probe the connections of a specific person they believe was a suicide bomber tied to Islamic State militants.
Turkish police fired tear gas and water cannons at May Day demonstrators in Istanbul as crowds attempted to defy a government ban on assembling in iconic Taksim Square.
Relations between Armenia and Turkey suffer in part because Turkey refuses to recognize the 1915 Armenian genocide. But improving relations will prompt that recognition.
An unconfirmed report claimed the Islamic State may have beheaded a second British hostage Saturday, the same day the militants released 49 other hostages unharmed.