The United States has informed Congress and its allies in Europe about Russian advances on a new, space-based nuclear weapon designed to threaten America’s extensive satellite network, according to current and former officials briefed on the matter.

Such a satellite-killing weapon, if deployed, could destroy civilian communications, surveillance from space and military command-and-control operations by the United States and its allies.

At the moment, the United States does not have the ability to counter such a weapon and defend its satellites, a former official said.