The leader of the PLO, Yasser Arafat, established close collaboration with the Romanian Securitate service and the Soviet KGB in the beginning of the 1970s. The secret training of PLO guerrillas was provided by the KGB. However, the main KGB activities and arms shipments were channeled through Wadie Haddad of the DFLP organization, who usually stayed in a KGB dacha BARVIKHA-1 during his visits to Russia. Led by Carlos the Jackal, a group of PFLP fighters accomplished a spectacular raid on OPEC headquarters in Vienna in 1975. Advance notice of this operation "was almost certainly" given to the KGB.