Human activity threatens the “sustainability, stability, safety, and security of the space environment,” a State Department official warned Thursday.

“For over five decades the global community has been inspired by humanity’s space endeavors and reaped the benefits of the use and exploration of outer space,” the State Department’s Frank Rose, said during a speech near Washington, D.C. “Some may take these benefits for granted so we must educate the public about the consequences if the space environment were to become unusable.”

Rose, a deputy assistant secretary in the Bureau of Arms Control, faulted China and Russia for conducting anti-satellite tests.

“Today the outer space environment is becoming increasingly congested from orbital debris, and contested from man-made threats—such as debris-generating Anti-Satellite systems—that may disrupt the space environment, upon which we all depend,” Rose said, noting that China tested such a system in July and in 2007.

“The United States believes that these threats, which include the continued development and testing of destructive anti-satellite systems, are both destabilizing and threaten the long-term security and sustainability of the outer space environment including all who benefit from outer space including the scientific, commercial, and civil space communities,” he added. “Indeed, thousands of pieces of debris from the 2007 Chinese ASAT test continue to endanger space systems — as well as astronauts — from all nations, including China.”