The OPEC siege occurred on 21 December 1975 when Carlos the Jackal and five other Arm of the Arab Revolution attackers entered the OPEC building in Vienna, Austria and took more than 60 hostages. The attackers killed three people: a German policeman, Libyan delegate Yusuf al-Azmarly, and a plainclothes Iraqi security guard; they proceeded to release the hostages in Algeria and Libya, and they were forced to release the targets of the raid, the Saudi and Iranian oil ministers Ahmed Zaki Yamani and Jamshid Amouzegar, as they would not be allowed to leave Algeria unless they did so. The raid was an operational failure, but OPEC did not hold another summit for 25 years.
The plan for the OPEC siege originated with the renewed Kurdish rebellion against Ba'athist Iraq, ruled by dictator Saddam Hussein. Saudi Arabia and Iran both supported the uprising against Hussein, and they promised to fund the Kurdish forces in their rebellion. Hussein, who was allied to the Popular Front for the Liberation of Palestine - External Operations (PFLP-EO), decided to cut a deal with its leader Wadie Haddad; PFLP-EO would be paid handsomely if it could abduct the Saudi and Iranian oil ministers, Ahmed Zaki Yamani and Jamshid Amuzegar, and kill them. As the Saudi and Iranian delegates to OPEC, they represented the oil interests of the two countries, and their deaths would ruin their countries' economies. Haddad entrusted command of the operation to Carlos the Jackal, who had become a celebrity for some terrorist attacks in England against pro-Israel businesses. Carlos and Anis Naccache ("Khalid") were entrusted with the operation, and they worked together with the German Revolutionary Cells members Hans-Joachim Klein and Gabriele Kroecher-Tiedemann and PFLP members "Youssef" and "Joseph". The team flew to Vienna in December 1975, meeting up with Iraqi intelligence forces under the charge d'affaires Riyadh al-Azzawi. al-Azzawi told the terrorists that they would fly to the friendly Libyan Arab Jamahiriya and then to Ba'athist Iraq, where they would have sanctuary.
On 21 December 1975, Carlos, Naccache, Klein, Kroecher-Tiedemann, Joseph, and Youssef entered the OPEC building through the front doors, and a receptionist told them where the meeting was being held. They carried with them Uzi submachine guns as well as pistols, and Youssef was tasked with the explosives. The terrorists entered the conference room, where they fired shots at the ceiling and shouted. Libyan delegate Yusuf al-Azmarly tried to attack Carlos, so Carlos pushed him to the ground and shot him several times. Kroecher-Tiedemann located an Austrian policeman and had him turn around, shooting him through the back of the neck and killing him. She put his body in an elevator and sent it downstairs, and she killed an Iraqi security officer (who had been one of the planners of the attack) when he tried to restrain her during the attack. Soon after, a squad of Austrian policemen arrived, finding the body of the policeman in the lobby before moving upstairs. Klein and Joseph fired on the policemen with Uzis from the hallway leading to the conference room, wounding one policeman, while Klein was wounded in the lower stomach area. The policemen were forced to retreat after Joseph threw a grenade at them, and Joseph kept watch in the hallway.
Managing the hostages
Meanwhile, Carlos had Youssef strap explosives to table legs in the conference room, and he located Yamani and Amouzegar. He told the crowd of hostages that he was Carlos, and he met with Venezuelan oil minister Valentin Hernandez Acosta, telling him that he appreciated his country's pro-communist stance during the Cold War. Carlos decided to divide the delegates into the neutral section in the back-left of the room (Gabon, Nigeria, Ecuador, Venezuela, and Indonesia), the friendly countries in the back to the right (Iraq, Libya, Kuwait, and Algeria), and the enemies (Saudi Arabia, Iran, United Arab Emirates, and Qatar) in the center. Carlos had Belaid Abdessalam, the Algerian Oil Minister and a doctor, take care of Klein while he had a British secretary deliver a communique from the terrorists, saying:
"To the Austrian authorities: We have taken the OPEC delegates hostage. We demand that the enclosed communique be read on Austrian state television and radio within two hours, and then at regular intervals every two hours. A bus with curtains at its windows will be provided to take us to Vienna Airport tomorrow morning at 7 o' clock. There, a DC-9 and a three-man crew will be ready to take off and carry us and our hostages to our final destination. Any delay, provocation, or unauthorized attempt to approach us will endanger the lives of our hostages. Signed, the Armed Wing of the Arab Revolution, Vienna, December 21, 1975."
The secretary took the communique and letter with her, and Carlos told her to take the letter to the police; she picked up the wounded Austrian policeman on the way out, delivering both the statements and the officer to the police. Abdessalam told Carlos that Klein's wound was deep and had to be opened, so Carlos had him taken to the police by Abdessalam, but not before taking his identification card; the police were unable to identify him, and when asked if he was a hostage, he said, "My fight name (nom de guerre) is Angie." Carlos then took Yamani into a room and told him that he was going to kill him because his lifting of the oil embargo against the United States was reason; he told him that he would personally kill him without hesitation and throw his body out the window if the Austrians did not follow through with the terrorists' demands.
Eventually, Chancellor Bruno Kreisky himself arrived in a helicopter, and an Austrian official notified him that the terrorists wanted to speak with the Libyan ambassador. The ambassador was in Prague, Czechoslovakia, so Kreisky agreed to buy some time and save lives by accepting Riyadh al-Azzawi's offer to mediate on behalf of Iraq. Eventually, the Austrians delivered the bus with the curtained windows, and the terrorists began to load the hostages onto the bus for transport to the Vienna Airport. They closed the curtains, preventing any attempt by the Austrian police to shoot the terrorists and save the hostages, and they released the 50 Vienna residents that had been held hostage, as Austria was not the target of the siege. The terrorists were taken to the airport, where they boarded the DC-9 operated by Muammar Gaddafi's personal pilot Neville Atkinson, and the group placed explosives under Yamani's seat before taking off. They first stopped in Algiers, Algeria, and Carlos the Jackal met with Algerian Foreign Minister Abdelaziz Bouteflika, who negotiated the release of the "friendly" hostages, with the 30 non-Arab hostages (except for the Iranian Amuzegar) being released to the Algerians. The terrorists intended to fly to Tripoli next, but Gaddafi was angered at the death of al-Azmarly, the Libyan delegate to OPEC. Gaddafi refused to give the terrorists another plane, and the terrorists were forced to return to Algiers again, releasing 10 more hostages before taking a Boeing 707 plane from the airport. The plane could fly to Baghdad nonstop, but Carlos was not allowed to leave the runway, as he would be shot down unless he released the remaining hostages. Carlos was forced to set Yamani and Amuzegar free in Algiers, and President Houari Boumediene offered the terrorists asylum and financial compensation in exchange for freeing the prisoners. The terrorists left with just the money, and the hostages were reluctantly freed by Carlos, who personally expressed regret at being unable to kill Yamani and Amuzegar. At the lounge of the airport, Anis Naccache asked to speat to Yamani, and he reached for his coat to draw a gun and shoot him. He was promptly arrested.
Bouteflika transferred $20,000,000 to Carlos, with Saudi Arabia bringing ransom money to the terrorists on behalf of Iran and the kingdom itself. Algeria gave the hijackers asylum before giving them transport to Aden, South Yemen (where the guerrillas were based). Haddad was infuriated, as he had given orders to kill the hostages if the government refused to comply with the demands of the terrorists; Carlos was expelled from the PFLP, and the subsequent Operation Entebbe led to the breakup of the German Revolutionary Cells as well. The OPEC siege did more harm than good to the guerrillas, and Carlos would form the Organization of Armed Struggle in 1977 after Haddad's death.