The head of MI5, Ken McCallum, has issued a stark warning about the increasing terror threat from children in Britain. Over the past three years, investigations involving minors have tripled.

The head of MI5 says Britain is facing a staggering rise in attempts at assassination, sabotage and other crimes backed by Russia and Iran.

The head of Britain’s domestic security service said Russia’s military intelligence service was pursuing “dangerous actions conducted with increasing recklessness.”