I've messed up a bit, I was trying to refer to the claim by the British Government that there were weapons of mass destruction hidden in Iraq, whereas that turned out to be inaccurate.
That was claimed to be the reason why we joined the conflict.
But the conspiracy claim is that they knew there were no active WMD programs (there were programs which could have been resumed when desired) and the true motivation was to steal oil.
The evidence is quite clear that Saddam wanted people to think he had WMDs because he felt that would make them fear him more. It worked the world's intelligence agencies believed it. It simply had the reverse result than the one he expected.
What did the UK or US have to gain from acting other than WMDs? What did the US or UK take from Iraq? Far from taking any treasure or oil from Iraq we gave blood and treasure. The US spent a fortune in Iraq to try to build a functioning democratic state. What did we have to gain from such beyond Iraq being a democratic state? Nothing.
Conspiracy theorists completely ignore the inability to identify any ulterior motive that pans out. What is there to gain in fighting ISIS beyond fighting extremism? There would have to be some gain.
This is not the case of the Nazis taking dead German prisoners and sticking Polish Army uniforms on them an dpretending they attempted an invasion of Germany and thus Germany has a right to invade Poland. The Poles denied such and it was quite obvious the Germans saged it to provide a bogus pretext. The goal was clear to see- they wanted to invade Poland to annex it and the pretext was for such purpose.
ISIS admits they killed the prisoners
ISIS says they will kill more innocent people including prisoners.
ISIS has comitted various atrocities not unlike Nazi mass executions. Their war crimes are not in question.
It is not the case like in 1939 where Poland denied invading Germany and the claim they did was absurd and clearly staged.
In the meantime there is no ulterior benefit that destroying ISIS could provide, the only benefit is the one of eliminating an enemy that is committing heinous acts.