Evidence that Russia is racing to perfect a nuclear-armed spacecraft to target Western satellites is sparking the U.S. and its Allies to strengthen their space defenses.

US officials have said a nuclear detonation would render portions of low-Earth orbit useless for up to a year.

Nuclear weapons are the most powerful and frightening tools ever created by humanity. With over twelve thousand warheads spread across the globe, these devices hold enough destructive force to end ...