This isn’t a terribly controversial view – it’s been taught in International Relations courses for the last n years, where n is quite large: the system of order among “modern” states is maintained by balance of power (which can catastrophically fail, as in WWI), while postmodern states (broadly, Europe plus Anglosphere post-2003) rely on transnational institutions and shared cultural values.
This isn’t entirely daft – trusting France not to harbour murdering terrorists is broadly safe (notwithstanding what some of the more deranged people on the US right may think); the same is demonstrably false for Iraq (which doesn’t mean Saddam was involved in 9/11, but he did provide sanctuary for al-Qaida-ites afterwards) and certainly not something you want to leave to trust for Syria or Pakistan.
The difficult bit is dealing with states in transition from modern “we hate everyone who isn’t us and my enemy’s enemy is my friend” to postmodern “we don’t actually hate the rest of the world at all – hey, we’re all people” – like most of Asia (outside the ex-USSR, where things don’t really seem to be improving), like Iran, and maybe like China.
Irrespective of WMD or no WMD, al-Qaida or no al-Qaida, it’s difficult to feel sad about the Iraq war. One of the world’s nastiest bastards is gone, and at the very worst case scenario we won’t make things much worse than they have been. On the other hand, it’s going to be decades before Iraq is democratic (in the sense of a commitment to democracy, rather than in the sense of having elections to pick the next tyrant) and secure. There was no good option.
However, if we were to destabilise Iran’s transition to democracy so that Iranians felt it was being imposed by external imperialists, this would be a genuine tragedy. And that’s where liberal imperialism falls apart – you CAN’T force the Iranians to democratise; that will make everything a million times worse. Unless the bad government you’re toppling is as bad as or worse than Saddam’s, which is rare, the “yes, but they’re our bastards” reaction kicks in among the people.
So where does that leave liberal imperialism, outside of Iraq, Afghanistan and North Korea? There isn’t anywhere else ruled by nasty enough bastards for an invasion to be welcomed even as grudgingly as the Iraq invasion. If we back democrats too strongly, then they’ll be discredited in the eyes of the people.
So whether you view the doctrine as scary or good, it’s not applicable in more than 2% of the world’s “modern” or “pre-modern” regimes anyway. Which is nice, or a shame, respectively.