For the past century, war has been fought in three domains: land, sea, and air. But now, there is a fourth. As America and China rush to establish bases on the Moon and Mars, Ukraine and Russia try to jam one another's satellite signals, and middle sized powers are learning how to protect themselves from enemy space weapons. Many countries now field Space Forces alongside armies, navies and airforces. How close are we to the first space war? And what will it look like? And who would win? Roland