A British teenager who killed three young girls at a Taylor Swift-themed dance event was jailed for at least 52 years on Thursday, for an attack Prime Minister Keir Starmer called one of the most harrowing moments in Britain's history.

A British teenager on Thursday repeatedly interrupted the start of his sentencing for murdering three young girls at a Taylor Swift-themed dance event last July, shouting from the dock that he was unwell before being removed.

The British navy said Wednesday that is ramping up measures to protect its waters from secret Russian operations after identifying a Russian spy vessel in UK waters for the second time in weeks.

The Royal Navy has been monitoring a Russian spy ship after it was spotted around UK waters earlier this week, the defence secretary has told MPs. John Healey said the vessel, Yantar, was used for gathering intelligence and mapping the UK's critical underwater infrastructure.

Britain on Wednesday warned that it faced a growing threat of aggression from Russia, asserting that a Russian spy ship had passed by the English coast for the second time in three months.