US government officials, in private sessions on Capitol Hill Friday, repeatedly declined to give details of radiation measurements at the stricken Japanese nuclear complex, saying the situation is shrouded in a "fog of war." Separately, the Obama administration said Friday "miniscule quantities" of radiation from the Japanese nuclear accident were detected Friday at a monitoring station in Sacramento, Calif., a day after similar traces of radiation were detected in Washington state. The administration said the levels of the radioactive isotope xenon 133 were approximately equivalent to one-millionth the dose received from the sun, rocks or other natural sources. The Obama administration's reluctance to detail in public what it is learning from radiation-detection operations around the damaged Fukushima Daiichi complex in Japan highlights a broader sensitivity in the US's posture toward a stricken ally. The shift comes after statements Wednesday by the head of the US Nuclear Regulatory Commission that painted a grimmer picture of the nuclear crisis than Japanese had offered, and suggested that the US didn't trust the information coming from the Japanese government.