British police have re-arrested two men under the National Security Act on suspicion of assisting Iranian intelligence services. The pair were previously arrested in connection with an incident last month at a US Air Force base in England (RAF Fairford), which has been used to launch attacks against Iran. Lawrence Taylor, head of UK counter-terrorism policing, stated that the investigation is "extremely complex" and there is a high suspicion of Iranian state involvement. UK Prime Minister Andy Burnham previously called the plot "almost certainly" directed by Iran's Islamic Revolutionary Guard Corps. Ken McCallum, head of the UK's domestic intelligence service, warned that Iran and Russia are expanding attacks on UK military bases. Iran denies involvement.