for the future were being considered many of the British staff were flown to Francistown in Botswana (then Bechuanaland) on a temporary basis to build a small transmitter to broadcast BBC World Service into what was Rhodesia, that country having declared UDI in November 1965. In the light of the fire damage and the deteriorating security situation in Aden it was decided to move the transmitters up the coast to the Omani island of Masirah. The Perim station was shut down and the transmitters moved before the end of 1966. British withdrawal and aftermath The British presence continued until 1967 when the island became part of the People's Republic of South Yemen. Before the handover, the British government had put forward before the United Nations a proposal for the island to be internationalised as a way to ensure continued security of passage and navigation in the Bab-el-Mandeb, but it was refused. Soon after independence in November 1967, South Yemen extended its territorial waters to 12 miles, which would include the waters between Perim and the mainland. Despite fears expressed by the British government and others, there was no interference with international shipping, until 1971 when the new radical Marxist government of what was now the People's Democratic Republic of Yemen (PDRY) allowed a group of PFLP guerillas to attack an Israel-bound tanker in the Bab-el-Mandeb from Perim. During the October War, South Yemeni artillery on Perim, along with Egyptian naval units, imposed an undeclared blockade at the southern entrance of the Red Sea. However, after the 1973 blockade, there were to be no further cases of interference with international shipping. The PDRY established close political and military ties with the Soviet Union which resulted in Soviet naval forces gaining access to the former British naval base at Aden as well as to the islands of Perim and Socotra. This strong Soviet military presence faded rapidly after the 1986 military coup in South Yemen and the advent of Perestroika under Mikhail Gorbachev. Perim Island Airbase Perim Island Airbase is located on Perim Island within the Bab el-Mandeb strait; the strait being crucial to Saudi oil production, with Saudi Arabia making up 12-17% of the industry, the largest share by any one sovereign nation. Perim Island is strategically located at the exit of the Red Sea, and at the tail end of the Suez Canal, leading to the recent creation of an