The Marshall Islands, scene of massive U.S. nuclear tests in the 1950s, is suing the United States and eight other nuclear-armed countries, accusing them of failing in their obligation to negotiate nuclear disarmament.
It has accused all nine nuclear-armed states of "flagrant violation of international law" for failing to pursue the negotiations required by the 1968 Nuclear Non-Proliferation Treaty.
It filed one suit specifically directed against the United States, in the Federal District Court in San Francisco, while others against all nine countries were lodged at the International Court of Justice in The Hague.
Reuters reports the action is supported by South African Nobel Prize winner Archbishop Desmond Tutu, and the Nuclear Age Peace Foundation, an anti-nuclear group.
Archbishop Tutu says the failure of these nuclear-armed countries to uphold important commitments and respect the law makes the world a more dangerous place.
The Nuclear Age Peace Foundation is a U.S.-based non-partisan advocacy group working with the Marshall Islands and its international pro-bono legal team.
The Marshall Islands was occupied by Allied forces in 1944 and placed under U.S. administration in 1947.
Between 1946 and 1958, the United States conducted repeated tests of hydrogen and atomic bombs in the islands.
One, on March 1, 1954, was the largest U.S. nuclear test, code-named Bravo.
It involved the detonation of a 15-megaton hydrogen bomb on Bikini Atoll, producing an intense fireball followed by a 32 kilometre mushroom cloud and widespread radioactive fallout.
The Marshalls government says the blast was 1,000 times more powerful than that at Hiroshima.
A copy of the suit against the United States made available to Reuters says that it is not aimed at seeking compensation from the United States for the testing in the Marshall Islands, which became an independent republic in 1986.
In a statement, the Marshall Islands Foreign Minister Tony de Brum said his people have suffered the catastrophic and irreparable damage of these weapons, vowing to fight so that no one else on earth will ever again experience these atrocities.