A senior Hamas official said Wednesday that the killing of the Palestinian movement's chief Ismail Haniyeh "will not go unanswered".
"The assassination of leader Ismail Haniyeh is a cowardly act and will not go unanswered," Hamas policial bureau member Musa Abu Marzuk said in a statement.
Palestinian President Mahmud Abbas said the killing of Hamas chief Ismail Haniyeh was a "cowardly act" and urged Palestinians to remain united against Israel.
"President Mahmud Abbas of the State of Palestine strongly condemned the assassination of Hamas leader Ismail Haniyeh, deeming it a cowardly act and a serious escalation," Abbas's office said in a statement.
"He urged our people and their forces to unite, remain patient, and stand firm against the Israeli occupation."
Meanwhile, Hamas's armed wing said Wednesday that the killing of its political leader Ismail Haniyeh takes the war with Israel to a "new levels," warning of repercussions for the entire region.
"The criminal assassination of leader Haniyeh in the heart of the Iranian capital is a watershed and dangerous event that takes the war to new levels and will have enormous consequences for the entire region," the Ezzedine al-Qassam Brigades, whose fighters are engaged in fierce battles with Israeli troops in Gaza, said in a statement.