1981? That's not evidence of what the Iraq were doing in 2003.
Also, the IAEA refused to let the U.S. remove 500 tons of Uranium we found.
It looks like that was eventually sent to Canada. The argument is that it wasn't "weapons grade." I don't know how to assess that.
If possible weapon-making material is there but isn't processed and there's no ongoing project of making weapons, then are there WMDs? Is preemptive war necessary or advisable, given what the costs would be?
The yellowcake is uranium ore. It is to weapons grade uranium as iron ore is to weapons grade steel - it needs to be precisely refined and specially treated. A big pile of yellowcake yields a little pile of highly enriched uranium.
As folks above have mentioned, at least one centrifuge (specially designed only to enrich uranium) was recovered buried in the rose garden of of a top guy in the Iraqi weapons program.
One of the biggest effects of the invasion of Iraq, was disrupting the nuclear proliferation ring of AQ Khan, father of the Pakistani nuclear weapons program. As a result, the Libyan program was dismantled and destroyed.
The gist of the AQ Khan ring was that a few countries would split up the programs and then share the results - one would focus on enriching uranium, another would work on design, another on missiles for delivery and so on. That is why you have Iranians in North Korea today, and North Koreans at Iranian enrichment sites like Fordo.
After Iraq had their Osiriak reactor destroyed, they continued to import and stockpile yellowcake. They had no industrial use for it, they were just trying to build up the materials ahead of time to enable a fast breakout, in case sanctions or embargoes were put on them when they started large scale enrichment
Most people won’t recognize the true threat until it knocks out the power supply to their American Idol final or X-Box and vaporizes a half million Americans.