The British military has been jamming or blocking satellites from other countries in order to defend itself from hostile threats, the BBC has been told. The RAF has been using a ground-based system for the past year, which a defence source said had already been used "to deter our adversaries". It is understood the system could be used to prevent a hostile nation's satellites from tracking the movement of the UK's nuclear armed submarines or other sensitive military operations, such as those involving special forces. It comes as the head of the RAF said the UK faced "unprecedented threats" from...