No idea how WWII was caused by "false propaganda". The Nazis in Europe, Pearl Harbor.
Or the American Revolution, Korean War, and so forth.
As for the Iraqi WMD's I'm not sure it that was intentionally false or simply bad intelligence.
That's easy.
The Allies started WWI when the Russians ordered the Serbian BlackHand to train and arm Princip.
But WWII was started by the illegal starvation blockade of Germany in WWI and the Treaty of Versailles stealing half of Germany.
Pearl Harbor was caused by the illegal economic sanction on Japan, and Pearl Harbor was deliberate that we knew about months in advance, since the Japanese did not know we had broken their code.
The Korean war was caused by anti-Bolsheic propaganda, where the US was backing those who had collaborated with the Japanese, and Syngman Rhee was wanted for bank fraud.
With Iraqi WMD, it had to be all deliberate lies.
For example, they claimed Saddam had mobile bio-weapons labs, and it was obvious those trucks were open to the air, and were for generating hydrogen for artillery balloons.
We even knew where he had purchased these hydrogen generator trucks, but I do not remember exactly.
Ambassador Wilson was sent to Niger to check out the yellow cake purchases, and it turned out it was a decade earlier for the Osiraq nuclear reactor the French has been hired to build and run.
So there was absolutely no possible nuclear weapons program, in any way.
Nor did Saddam ever have sarin or VX.
The only gas he had was the mustard gas the US had given him during the war with Iran.