OPEC siege

On December 21, 1975, six military officials attacked a meeting of OPEC leaders in Vienna, Austria. The attackers took more than 60 hostages after killing an Austrian policeman, an Iraqi OPEC security officer, and a Libyan economist. Many other individuals were wounded. 
The self-named "Arm of the Arab Revolution" group was led by Carlos the Jackal. The siege caused in complex diplomatic negotiations. It ended two days later, after flights to Algiers and Tripoli, with all the hostages and terrorists walking away from the situation. 
Since this was one of the first times that Arab states were targeted by terrorists also led to them being more active in antiterrorism efforts at the United Nations.