They began as supply mules. Now ground robots evacuate the wounded, hold trenches and even do the killing. By Maria Varenikova and Paul Mozur Operating out of a Tokyo high-rise, a military ...

Make sense of the day’s news and ideas. Catch up on big news, and wind down to end your day. The biggest stories of our time, in 20 minutes a day. A guide to understanding the news, made for readers ...