This is worth looking at, considering the potential threat to the UK.
JTIC briefing: LNG tanker terrorism
As the global market for liquefied natural gas (LNG) continues to expand rapidly, with ever more carriers ploughing the oceans, there is still concern that terrorists will attack LNG infrastructure. Fears that terrorists will use an LNG carrier to create an explosive vapour cloud over a city are misplaced, according to US studies, but LNG carriers still present tempting targets for publicity-seeking terrorists.
The threat from maritime terrorist attacks was demonstrated on 12 October 2000 when a small boat loaded with explosives rammed the USS Cole in Aden harbour. Two years later, the same tactic was used against the oil tanker Limburg, which was rammed several miles off the Yemeni coast. One crewman was killed and several thousand barrels of oil spilled in an attack that seemed intended to disrupt oil supplies.
Maritime aspects of the "war on terror" are seldom discussed by the media, which is why I have tried to highlight them on this thread.