Ties between Israel and its former Muslim ally, Turkey, have plummeted in the wake of a United Nations report on a deadly Israeli raid off the coast of the Gaza Strip more than a year ago.

Israel has expressed regret over Turkey’s decision on Friday to expel the Israeli ambassador and suspend military ties between the two countries. Turkey is furious after a United Nations report charged that Israel used excessive force in a commando raid on a Gaza aid flotilla last year in which nine Turkish activists were killed.

In a statement by the Prime Minister’s Office on Saturday, Israel said it “cherishes the significant ties, past and present, between the Turkish and Jewish peoples” and therefore it had sought to settle the dispute peacefully. But Israel said it could not meet Turkey’s demand to apologize for the flotilla raid because Israeli troops acted in legitimate self-defense.

While describing Israeli actions as unacceptable, the U.N. report also said that Turkey did not do enough to prevent a violent confrontation, and that some Turkish activists were armed with iron rods and knives used to attack Israeli commandos.

Israel expressed regret over the loss of life but that was not enough for Turkey, which has been highly critical of the Jewish state since Israel’s bloody invasion of the Palestinian-ruled Gaza Strip in early 2009. Israeli analyst Ra’anan Gissin, a former government spokesman, says Turkey’s Islamist government is not interested in improving ties with Israel.