Reactions to the Gaza flotilla raid on 31 May 2010 ranged from fierce condemnation to strong support for Israel. Israel expressed regret over loss of life in the Gaza flotilla raid, yet stated that the operation was a "clear case of self defense". Prime Minister Benjamin Netanyahu apologised for the incident in March 2013, which he said was necessitated by the Syrian civil war. The incident also drew attention to the blockade of the Gaza Strip, which was condemned. Secretary-General of the United Nations Ban Ki-moon called for a full investigation and urged Israel to provide a full explanation. Many countries called for an international investigation and civilian protests erupted around the world.Four countries downgraded their diplomatic relations with Israel and/or withdrew ambassadors: