The UN's resolution 1540 obliges all governments to stop nuclear (and chemical and biological) bomb-making materials falling into terrorist hands.

ECONOMIST: Preventing nuclear trafficking is easier than policing it

The United States and its allies invaded Iraq in March 2003, accusing Saddam Hussein's regime of concealing stocks of chemical and biological weapons, long-range missiles and efforts to develop a nuclear bomb from U.N. weapons inspectors.

CNN: Bush in Ohio defends war

The United States and its allies sought explicit Security Council authorization to use force against Iraq, warning that Baghdad was defying U.N. resolutions demanding it give up chemical and biological weapons, long-range missiles and efforts to develop a nuclear bomb.

CNN: Chirac: Iraq war undermined U.N.