I think he was referring to overly high expectations that some in the US might have had about how much progress could me made in Iraq. He is saying that because the US put so much (spent so much) into the war, there was an expectation in the public that Iraq would develop into a mature democracy, for which he used Denmark as an example. But this hasn't happened, leading to the disenchantment about the Iraq war.

It is a puzzle to me. There must be some context that neither you nor I knows. I learn from Googling that "Denmark was the only country in the EU at the time in which the majority of the population supported the Iraq war" and that "Australia, Denmark, Poland, Spain and Britain" were the only countries that sent troops to help the United States. If somebody said "And the war didn't turn out to be a cakewalk," then I would know he was referring to a famous bellicose editorial piece he wrote. I wondered if Jeffrey could be referring to some prediction that Iraq would become a model democracy like Denmark, but I can't find anything like that.