It was a pattern which Sheridan would repeat many times - serving jail terms for refusing to pay the poll tax and a fine after taking part in blockades at Faslane nuclear submarine base.

BBC: The rise and fall of Tommy Sheridan and the left

The submarine headed back to its base on the Kola Peninsula, by the Barents Sea, which took five hours.

BBC: Eyewitness: Tragedy of Soviet nuclear submarine K-27

Meanwhile, Russia has sent a naval flotilla of seven warships led by an anti-submarine destroyer to its Syrian base at Tartus, according to Interfax news agency.

BBC: Envoy Kofi Annan presses Iran and Iraq over Syria crisis

Additionally, an unspecified number of aircraft, designed for anti-submarine warfare, will be stationed temporarily at a Venezuelan air base.

ECONOMIST: Ruling the waves