GPS signal under threat, Nature
"Concern over the US Global Positioning System (GPS) stepped up a notch today after a senior official from the US government's congressional watchdog warned that the US Department of Defense faced substantial challenges meeting its space-programme commitments."
"Lt. Col. Tim Lewallen, deputy director of GPS at Air Force Space Command at Peterson Air Force Base in Colorado, agreed with the GAO's conclusion that there is a risk that service could degrade. But he said the risk is very small."
GPS system 'close to breakdown', The Guardian
"US government officials are concerned that the quality of the Global Positioning System (GPS) could begin to deteriorate as early as next year, resulting in regular blackouts and failures or even dishing out inaccurate directions to millions of people worldwide."