China Conducted Nuclear Blasts in Tibet to Divert Brahmaputra River
tibet.net
tibet.net
1) It (supposedly) happened in March 2005, when world's (and US agencies') eyes were on Iraq war.
2) "<...> US authorities admitted to their Indian counterparts the complete failure of their satellites to detect the blasts"
Which is quite believable if nuclear blasts were low-yield as stated in the article.