Last month DoD released an updated space policy that officials said reflects how the environment has changed in recent years, specifically the emergence of non-state threats and the growing amount of derelict rockets and satellites -- "space junk" -- in orbit that pose a hazard to working systems, especially those launched and maintained by the United States.
According to the NASA Orbital Debris Program Office, more than 21,000 pieces of orbital debris larger than 10 centimeters exist in orbit, along with 500,000 smaller pieces and more than 1 million pieces smaller than 1 centimeter.
"Space capabilities have long provided strategic national security advantages for the United States," Deputy Defense Secretary Ash Carter said in a DoD press release. "This updated space policy institutionalizes the changes the department has made in an increasingly constrained budget environment to address the complex set of space-related opportunities and challenges."
In the press release acting deputy SecDef for Space Policy John Plumb addressed what the policy refers to as "international norms of responsible behavior related to the space domain" saying interference with systems would be "irresponsible in peacetime and during a crisis could be escalatory. The policy states this very clearly and it's a message we want to make sure people understand."
Veiled threats might deter those who would target our systems with malice, but they won't do much against dead objects hurtling around up there -- space's version of a dumb bomb. In fact back in 1978 NASA scientist Don Kessler warned of a doomsday scenario where a single collision causes a chain reaction of other collisions that wipe out everything after a couple of trips around the planet. (This scenario is known as the "Kessler Syndrome.")
Read DoD's new space policy document here.