There's a lot that I agree with in Michael Berubé's post here on the "sovereignty left", but I think this is actually an easy question to answer:
And it is in both camps’ interest to pretend that Kosovo, Afghanistan and Iraq were all part of the same enterprise: all three wars were wars of liberation for the Hawks, and all three were exercises in imperialism for the Sovereignty Left. The Hawks wound up agreeing, in whole or in part, with Bush’s premise that Iraq was the next logical front in the War on Terror. And the Sovereignty Left has never quite explained what American empire was established in the Balkans, and they’ve never quite explained why they opposed the Taliban from 1996 to 2001 but opposed the Taliban’s removal after al-Qaeda’s strikes against the US. But both groups share the common goal of aligning supporters of war in Kosovo and Afghanistan with supporters of war in Iraq.
I have no particular reason to defend the individuals in Berubé's crosshairs, but I certainly think we could all do with a more critical review of what, exactly, has been happening in Kosovo since the war in 1999. First of all, it's quite clear that the early assurances from Washington and other NATO capitals that Kosovo would not be partitioned off from Serbia have proven false -- it's now almost certain Kosovo will be recognized as an independent state. The only remaining question is what price Russia will extract for not vetoing such a decision by the UN.
But specifically to the issue of American Imperialism in the Balkans, we see that in fact Kosovo is now home to one of the largest US bases in Europe, Camp Bondsteel. It seems to me that if one of the arguments that the US is conducting an imperial war in Iraq revolves around the construction of permanent US bases in that country, the construction of a massive permanent base in Kosovo is certainly relevant. I have no idea what arguments Chomsky is making these days, but "it's all about oil" was the argument Chomsky was making when I last read his works. Then there's people like Chalmers "America is an empire of bases" Johnson, who has repeatedly stated his arguments that the onward march of American bases across the planet is wholly imperial.
One of the issues that concerns me is the almost flippant disregard for national sovereignty that prominent liberals (predominantly in the anglosphere) have begun to take, especially after the UN confirmed the "responsibility to protect", a doctrine which essentially lays the groundwork for future humanitarian interventions. Even though the UN only officialized this doctrine less than two years ago, we're already seeing it used as a rhetorical club against powers like China for supporting Sudan at the UN.
I don't consider myself part of the "sovereignty left" that Berubé speaks of -- I supported and still support the NATO mission in Kosovo, with some misgivings -- but I think it's too easy to gloss over the real value that a norm of national sovereignty provides to international politics.
The problem is that this debate has not been marked by an abundance of clarity. When people talk about "national sovereignty" they tend to mean one or more of several different but related concepts. Dictators like Milosevic or Putin use sovereignty when what they really mean is autonomy, a concept that doesn't quite have the same ring to it.
To clarify: in IR-speak, de jure sovereignty is the recognized right of a government to govern a territory. (Most countries.) De facto sovereignty is the ability to do so absent international recognition. (Taiwan.) Autonomy is the right or ability of a sovereign government not to have its acts interfered with by another power. The concepts are obviously closely related, but the ways in which they are distinct are important to this debate.
I think once you clarify these concepts, the division between Kosovo and Bush's wars becomes clear: Kosovo was unquestionably a major breach of Yugoslavia's autonomy, but not so much of its sovereignty. This is why I mentioned the promises of no partition earlier -- this was important in selling the war back then. Yugoslavia was recognized as the legitimate government of Kosovo, even if it was doing illegitimate things. We didn't want to destroy the Milosevic regime, we simply wanted them to stop. (Ending Milosevic's regime took other measures, that were more effective.)
The wars in Afghanistan and Iraq, on the other hand, were clearly about sovereignty: neither Hussein nor the Taliban were legitimate governments, in Washington's eyes. It was not enough for either state to stop doing the things they were accused of -- those governments had to lose their sovereignty and be replaced by different governments.
Of course, this hasn't turned out so well in either of those cases -- certainly not as well as Kosovo. This is why I think "a curious worship of the norm of sovereignty" is actually a reasonably healthy thing to have, at least in so far as we're talking explicitly about actual sovereignty and not autonomy. If I can venture a hypothesis, I think that America is in a much better position to dictate the proper behavior of a government than dictating who is the legitimate government. Look at Iran where the international community is reasonably united on the idea that Iran shouldn't have nuclear weapons, but most of America's allies also think Iran can reasonably ask the US to forswear regime change.