The UN didn't fail to take action. As we now see, the UN was taking precisely the correct action. It was sending its inspectors into Iraq. The inspectors were doing a good job. The US action of kicking out the inspectors and attacking Iraq is now being blamed for the disappearance of the materials that were discussed in the link I posted in this thread, as well as stockpiles of conventional weapons which are now being used to kill US soldiers as well as innocent Iraqi civilians.