China has been blocked, by American diplomatic pressure, from buying several "counter stealth" Vera radars from a Czech Republic manufacturer. The Vera radar claims to defeat the stealth capabilities, although there has been little opportunity to test this in a combat situation. But on paper, the Vera radars are apparently a threat, and the United States was eager to prevent the Chinese from getting this equipment (which would threaten the effectiveness of F-117, F-22, F-35, B-1 and B-2  aircraft.)