The UK is facing an uptick of assassination attempts on its soil by Russia and Iran, the head of the domestic intelligence agency Ken McCallum said in a rare public speech given on Tuesday. McCallum called the increase in assassination attempts “staggering,” saying that the number of state-threat investigations undertaken by the MI5 had risen by 48% in the past year. He added that Russia and Iran often recruited criminals, from international drug traffickers to “low-level crooks,” to carry out attacks on their behalf. The agency chief singled out Iran as a major threat to the UK, saying agents…