Self-flying fighter jets, uncrewed submarines and drones will be at the centre of Britain’s future military under a defence plan being announced on Tuesday that reflects a world of conflicts transformed by technology.The plan prioritises £5 billion (US$6.6 billion) of investment in drones and a focus on autonomous systems to try to modernise and build up its depleted armed forces at a time of rising threats.The Defence Investment Plan has been repeatedly delayed as military leaders and Treasury officials wrangled over the cost of equipping the nation’s military for an increasingly dangerous world.Like other Nato countries, the UK is under pressure to increase defence spending to counter a more aggressive Russia and less reliable United States.John Healey resigned as defence secretary on June 11, accusing the government of being unwilling to spend enough on the military at a time of “rising threats”.Healey argued that UK defence spending must reach three per cent of GDP by 2030, citing a British intelligence assessment that Russia could attack a Nato member country by then.