Donald Trump has ordered work on the most ambitious missile shield in US history, one designed to destroy hypersonic missiles and prevent nuclear annihilation. The US president dubbed it the “Iron Dome for America” – a nod to Israel’s renowned air defence system. But the vision for Trump’s next-generation system, including space-based lasers, is actually much closer to Ronald Reagan’s so-called Star Wars programme, launched in 1983 at the height of the cold war. Developing a kind of Star Wars 2.0 would cost hundreds of billions of dollars. The technological challenges it faces are immense. Nuclear experts also warned the…