I don't think that the US invaded Iraq to defend the USD as a world currency - the USD was in no danger despite whatever Saddam was doing.
From what I understand, most people believe that the invasion was instigated by Neoconservatives who believe(d) that the creation of a free democratic state in the Middle East would be a stabilizing force, which would be beneficial for US foreign/security policy.
WMD seems to be an excuse, but the true reason is well-intentioned (from a US point of view), albeit self-centered and naive. To think it had anything to do with the USD is a bit conspiracy theorist.
(Iraq did change reserve currencies from USD to EUR in 2001, however their total foreign reserves are $53b, not enough to spark a multi-year, trillion dollar war)
You are forgetting that Iraq is the third biggest export of oil in the world, and that the "reserve currency" of the world currently is what people call "petrodollar"
It is not a conpiracy theory, it is simple and obvious, many people outside US saw through the WMD accusation immediately, if everyone switched to buy oil with anything other than USD, US would be unable to print more money to keep getting indebted, and we all know that US currently has no way to sustain its economy without growing its debt.
It is just a matter of pre-emptive defense of domestic issues, the US cannot risk at all, even a minor risk, of other countries not allowing it anymore to generate loads of debt, because it depends deeply on it to sustain all its government spending.
Libya for example had the same kind of "protests" that turned into civil war, EVERY year, the only difference between the year they got a "no-fly" from others, is that Gadaffi also stopped selling oil for USD.
It is VERY CLEAR that US consider this a serious threat (and it is)
From some points of view, the government had no choice but to go to war...
From what I understand, most people believe that the invasion was instigated by Neoconservatives who believe(d) that the creation of a free democratic state in the Middle East would be a stabilizing force, which would be beneficial for US foreign/security policy.
WMD seems to be an excuse, but the true reason is well-intentioned (from a US point of view), albeit self-centered and naive. To think it had anything to do with the USD is a bit conspiracy theorist.
(Iraq did change reserve currencies from USD to EUR in 2001, however their total foreign reserves are $53b, not enough to spark a multi-year, trillion dollar war)