Iran’s reckless behaviour risks triggering a “disastrous” escalation of hostilities in the Middle East, the head of the British military has said. Chief of the Defence Staff General Sir Nick Carter said Iran made a “big mistake” when it targeted the Mercer Street tanker, killing a Briton and a Romanian. The drone attack on July 29 off the coast of Oman led to international condemnation of Iran after the UK, United States, and Israel pinned the blame on Tehran. Carter told BBC Radio 4’s Today programme: “What we need to be doing, fundamentally, is calling out Iran for its very reckless behaviour. “They made a big mistake on the attack they did against the Mercer Street vessel last week because, of course, that has very much internationalised the state of play in the Gulf.” He added: “Ultimately, we have got to restore deterrence because it is behaviour like that which …