WASHINGTON — Deliberate interference with space systems either owned or relied upon by the U.S. Department of Defense will be deemed “irresponsible” during peacetime and possibly “escalatory” during crises, the Pentagon has declared.

In a space policy document signed Oct. 18 by Deputy Defense Secretary Ashton B. Carter, the Pentagon appears to have drawn a line in the sand on all types of deliberate interference with space systems. The directive declares the sustainability and free use of the space environment to be a “vital” U.S. national interest.

“Purposeful interference with U.S. space systems, including their supporting infrastructure, will be considered an infringement of U.S. rights,” the document, publicly disclosed without fanfare Nov. 21, states. “Such interference, or interference with other space systems upon which the United States relies, is irresponsible in peacetime and may be escalatory during a crisis. The United States will retain the capabilities to respond at the time and place of our choosing.”

The directive is intended to codify for defense purposes U.S. President Barack Obama’s National Space Policy issued in June 2010 and the U.S. National Security Space Strategy signed by then-Defense Secretary Robert M. Gates and Director of National Intelligence James R. Clapper and released in February 2011. Like those earlier documents, the Pentagon policy emphasizes sustainability of what is often characterized as an increasingly congested and contested space environment, international cooperation and government reliance on commercial space capabilities.

In an article posted online Nov. 21 by the Pentagon-controlled American Forces Press Service, Carter said the space policy update, the first since 1999, “institutionalizes the changes the department has made in an increasingly constrained budget environment to address the complex set of space-related opportunities and challenges.”

Government and industry sources said the new directive departs from the 2010 and 2011 policies in a couple of areas, including the Pentagon’s position on deliberate interference to U.S. space systems. According to these sources, the Pentagon language carries a sharper edge.

The National Space Policy, for example, asserts the U.S. right to self-defense in space and states that purposeful interference with space systems or infrastructure is a violation of a nation’s right. But neither that document nor the National Security Space Strategy uses the term “escalatory” — which implies a forthcoming response — in characterizing interference.

The American Forces Press Service article quoted John F. Plumb, acting deputy assistant secretary of defense for space policy, as saying the directive is a declaration of how the U.S. government would view interference with space systems. “The policy states this very clearly and it’s a message we want to make sure people understand,” he said in the article.

One space policy expert said the language is intended to serve as a red line but could be interpreted as provocative by potential adversaries. This source said it paints interference, which comes in a variety of forms, with a broad brush that could limit the Pentagon’s flexibility in certain situations.

These sources also pointed to the new policy’s emphasis on the deterrence value of international coalitions in space, a notion they said is not as fully embraced in the earlier documents. The new policy says the Defense Department will seek to expand international cooperation in space to enhance “collective security capabilities” while forging closer ties with friends and allies. This, along with measures including promoting responsible behavior among spacefaring nations, will help deter attacks on U.S. or allied space systems in part by making architectures more resilient, the policy states.

The idea is not a new one.

As outlined by Obama administration officials during the past year or so, international cooperation will help deter aggression because an attack on one nation’s space systems would be regarded as an attack on all. In a section on deterrence, the National Security Space Strategy does in fact say that the Pentagon will pursue international partnerships “that encourage potential adversary restraint.”

The space policy expert, who spoke on the condition of anonymity, said similar language was left out of the National Space Policy because authors felt it might encourage risky or entangling alliances in the name of a theory that has not been proved.

The new policy also emphasizes the importance of space situational awareness capabilities and said efforts to modernize U.S. capabilities in this regard will integrate data from foreign and commercial sources. Space situational awareness refers to understanding all aspects of the space environment including the location of space objects and potential threats to satellites, both natural and man made.

The U.S. Air Force operates the world’s most sophisticated space surveillance system but other countries and the private sector are developing considerable capabilities of their own. The United States is actively pursuing space surveillance data sharing arrangements with other nations, while satellite operators have been seeking ways to enhance data sharing with the Air Force.

Like the previous documents, the new policy says that the Department of Defense will use commercial space capabilities “to the maximum practical extent,” so long as it is consistent with national security requirements.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...