The ceasefire agreement of April 1991 established a UN special commission, Unscom, whose role it was to dismantle the non-nuclear arsenal and to assist the International Atomic Energy Agency (IAEA) in dismantling Iraq's nuclear weapons
programme. Additional responsibilities included preventing so-called "dual use" exports with NBC or ballistic missile potential from reaching Iraq.
Unscom was charged with monitoring Iraq's compliance with the UN resolution. Sanctions were imposed until such a time when the inspectors could certify that all NBC programmes and their component agents and equipment had been destroyed. The sanctions continue to this day.
Unscom was forced out (by the UN, due to safety concerns) of Iraq in 1992, when mobs attacked the weapons inspectors. They did return, but were denied access to various buildings (mostly Presidential "Palaces") and in 1997 Iraq expelled all
US(!) inspectors. In October 1998 Iraq
ceased all cooperation with Unscom. It resumed it in November but in December the bombing began.
In December 1998, Unscom pulled out of Iraq amid complaints of obstruction by Iraq. Meanwhile, Baghdad claimed that the body was little more than a front for US spies (
with some justification; the presence of CIA agents was later confirmed by the US, UN and former inspectors).
It left ahead of Operation Desert Fox, 70 hours of US-British airstrikes designed to punish Iraq for failing to cooperate with the inspectors.Note: That's over six years of US "intelligence" embedded in Iraq that made damned sure Iraq couldn't fight back when invaded!
Unscom was disbanded and replaced in December 1999 by the UN monitoring, verification and inspection commission (Unmovic) funded by limited sales of Iraqi oil. Resolution 1284, which set up Unmovic, specified that if Iraq cooperated with the new inspection team for 120 days, sanctions would be suspended and then lifted. Iraq rejected the plan as a "criminal resolution" that would "transform Iraq into a protectorate governed from outside with Iraqi money".
On November 18, 2002, a team of about 30 weapons inspectors, led by the chief weapons inspector, Hans Blix, and the director of the IAEA, Mohammed el-Baradei, returned to Baghdad to begin Unmovic's work.
They were withdrawn due to the impending US invasion in 2003.
http://64.233.167.104/search?q=cache:Y5LBzbhM1p4J:www.guardian.co.uk/theissues/article/0,6512,794275,00.html+UN+Weapons+Inspection+Iraq+history&hl=en&lr=lang_en