The Mainichi Daily News of Japan has reported that Nagasaki Mayor Tomihisa Taue (photo left) and Hiroshima Mayor Kazumi Matsui (photo right) have expressed dismay at U.S. nuclear weapons tests carried out in November 2010 and March 2011. Citing U.S. President Barack Obama's epoch-making speech calling for a nuclear-free world in Prague in April 2009, Hiroshima Mayor Matsui said, "We call upon the U.S. to withhold from any actions that could generate misunderstandings among those who are sincerely hoping for the elimination of nuclear weapons." "We have yet to learn what significance the experiments have, but we cannot tolerate them if they are to lead to the development of new atomic weapons," said Nagasaki Mayor Taue. So-called "sub-critical" nuclear weapons testing has continued at the Nevada Test Site even after the September 1992 moratorium on full-scale underground nuclear weapons blasts announced by President George H.W. Bush. For example, on February 14, 2002 (Valentine's Day) -- the very same day George W. Bush's Energy Secretary Spence Abraham gave his thumbs up to Yucca Mountain's "suitability" as a radioactive waste dump, and announced the Nuclear Power 2010 Program -- a "sub-critical" nuclear weapons test was also carried out in Nevada. Using conventional explosives laden with plutonium, the data collected from these tests are fed into super computers, capable of "advancing" nuclear weapons designs without carrying out full-scale detonations.