Laser tag

摘要

LASER WEAPONS orbiting in space and warplanes that shoot down rockets sound like the doodlings of a teenage boy. Both appear in the Trump administration's missile-defence review, published on January 17th. It lays out a celestial vision of homeland defence that looks cosmically expensive and technologically dubious. America does not skimp on shooting missiles out of the sky. Its 2018 budget allocated $19.3bn to the task-roughly equivalent to the entire defence budget of Canada or Turkey. Since 2001 it has splashed out over $13obn. Some of that is spent on ship-based Aegis and land-based Patriot and Terminal High Altitude Area Defence (THAAD) systems, which are aimed at short or medium-range missiles. Intercontinental ballistic missiles (ICBMS) fly higher and faster.