The U.S. government has used its ground-based space surveillance network to warn Chinese authorities of debris threats to Chinese spacecraft on 147 occasions in the past year as part of its policy of providing advisories “to all government and private-sector satellite operators,” a U.S. State Department official said June 13.

Frank A. Rose, the department’s deputy assistant secretary in the bureau of arms control, verification and compliance, said the U.S. Strategic Command’s Joint Space Operations Center (JSPOC) has delivered similar notifications to Russian authorities on 252 occasions in the past 12 months.

Speaking in Prague at the “Space Security Through Trans-Atlantic Partnership” conference organized by the European Space Policy Institute and the Prague Security Studies Institute, Rose said the JSPOC has sent a total of 677 close-approach notices to government and industry satellite operators since May 2010 that concerned only the debris left by China’s intentional destruction, with a ground-based missile, of an aging Chinese weather satellite in low Earth orbit in 2007.

Rose said providing the global community with warnings of debris that might collide with a satellite is part of the U.S. government’s policy of building trust among spacefaring nations and promoting the safe use of space for all nations that use it. Another part of the policy is inviting operators to visit JSPOC, which a Russian government delegation will do later this year, Rose said.

He said the U.S. government is still reviewing a proposed European Union “Code of Conduct for Outer Space Activities,” a nonbinding document that the EU hopes all spacefaring nations will sign. He said the United States first needs to determine “what, if any, modifications are necessary” before subscribing to the code of conduct.