US conducts limited nuclear test The United States said Thursday it has conducted a "subcritical" nuclear test at an underground site to study the behavior of nuclear materials without triggering an atomic explosion. The test, conducted Wednesday in Nevada, aims to gather scientific data that will "provide crucial information to maintain the safety and effectiveness of the nation's nuclear weapons," the Energy Department said in a statement. Such tests "ensure that we can support a safe, secure and effective stockpile without having to conduct underground testing," said National Nuclear Security Administration head Thomas D'Agostino. Staff from the Nevada National Security Site, Los Alamos National Laboratory and Sandia National Laboratories conducted the experiment, known as Pollux. It was the 27th subcritical experiment to date. The last one, known as Barolo B, took place in February 2011. Subcritical nuclear tests, which do not trigger a self-sustaining chain reaction that would create a nuclear explosion, examine how plutonium behaves when it is shocked by forces produced by chemical high explosives. The United States halted underground nuclear tests in 1992. By then, it had conducted 1,032 tests since 1945, according to UN figures. Wednesday's test passed with little notice in the United States but drew sharp criticism from Hiroshima, the Japanese city destroyed by the first-ever nuclear weapon used in an armed conflict. Hiroshima was struck by the first of two US nuclear bombs dropped on the country near the end of World War II. "I wonder why President (Barack) Obama, who said he would seek a nuclear-free world, carried out the test," Hiroshima mayor Kazumi Matsui told reporters. "I wish he would take into account the feelings of the people of Hiroshima when making policy decisions," he said. Hirotami Yamada, 81, secretary general of the Nagasaki Atomic Bomb Survivors Council, said: "It is depressing that the United States cannot understand how atomic bomb survivors feel, despite our repeated protests." The test "is proof that the United States could use nuclear weapons anytime. Such a country is not qualified to be a world leader," he said.