Ted Galen Carpenter keeps pushing his “realism” that would ethnically partition Balkan states, but, not surprisingly, few listen. His latest critique of Mrs. Merkel and ourselves compels us to do something we have long resisted—to answer the mail.

In response to Carpenter’s attack on Merkel’s Balkan policy, it is worth restating our point: Angela Merkel was informing Belgrade in a very public manner that the era of partitions has ended in the Balkans. If Serbia wants to sustain the pretence of opposing Kosovo’s independence and slicing off a piece of Kosovo territory north of the Ibar River, it can forget about approval later this year to become a candidate member for EU accession. There is nothing wrong per se with Serbia asserting its sovereign right to refuse to accept the independence of Kosovo or trying to hold on to the north. It is also perfectly proper for the German chancellor, as a leading member of the EU community and someone with a profound historical memory of the damage that territorial irredentism can inflict on Europe—and in fact did inflict on Yugoslavia during the 1940s and 1990s—to end any illusions in Belgrade that Serbia can have it both ways by conditioning Serbia’s further integration into the European community of nations on the full acceptance of a core principle of European postwar stability: the abandonment of territorial claims on neighbors. Probably almost everyone in Europe (other than Greeks and Greek Cypriots) admits that letting the Republic of Cyprus into the EU while a major division existed in Cyprus was a mistake. It was also blackmail; Greece threatened to block the acceptance of other countries then ready for admission unless Cyprus was let in.

Carpenter walks on dangerous ground when he asserts the need to preserve “the option of partition to create more cohesive and stable political entities.” That was precisely the rallying cry of Slobodan Milosevic and his supporters who ignited the Balkan violence in the early 1990s in the name of a more cohesive and stable Greater Serbia and which drove every single Yugoslav republic out of Yugoslavia as well as the autonomous republic of Kosovo.

Carpenter’s desire to leave the door open for partition of Kosovo would tempt fate, and further violence, by opening the partition door for the ethnic groups of Serbia. What happens to the Albanians in the Presevo Valley adjacent to Kosovo? We ourselves had considered such a trade for north Kosovo but ruled it out (as all Western countries have) for fear of opening a Pandora’s box. For then there are the unhappy Muslims in Sandzak, whose interest in partition would likely prove unacceptable to Belgrade. Don’t forget the quiescent Hungarians of Vojvodina—the last autonomous republic of Yugoslavia in Serbia. What happens if one day they changed course and decided to seek to join with Hungary? And by the way, the Serbian government did not ”hint” at partition of Kosovo—their current Balkan negotiator told us and numerous others their goal was partition: “Serbia could not leave Kosovo empty-handed.”

Carpenter also wants to open up Bosnia to ethnic partition. Is it reasonable to think that Bosnia’s Muslims would calmly allow the Bosnian Serbs—after creating their Republika Srpska through horrific ethnic cleansing ignored by Carpenter—to depart Bosnia without a fight? And wouldn’t the Bosnian Croats try to emulate the Bosnian Serbs and seek union with neighboring Croatia, thereby obstructing Croatia’s final sprint toward agreed EU membership in 2013? Further, would the US and the EU upend the Dayton accords? If northern Kosovo is hived off to please Belgrade, should the restive ethnic Albanians in Macedonia be compelled to remain in that country rather than unite with kinsmen in Albania and Kosovo?

These are the kinds of untidy and real-world policy implications that Carpenter does not deal with, beyond his suggestion that the Europeans should deal with any problems left by their refusal to accept partition and his insistence that the U.S. “not help bail” Europe out of its “folly” of ignoring the benefits he sees in partitionism. But the Europeans have seen all this before—quite recently in fact—and they know exactly where ethnic-based partitionism leads. This does not mean that there is not a serious problem in north Kosovo that could well produce more violence. That problem must be carefully managed and Serb interests addressed as best as possible—no easy task.

We can all take some comfort in the fact that the German chancellor has absorbed the violent lessons of recent Balkan history and is so outspokenly opposed to ethnic-based partitionism there. Her tough message to Belgrade is firmly supported by Washington, and so far Belgrade appears willing to try and live with it.

Morton Abramowitz is a senior fellow at The Century Foundation and James Hooper is a managing director of the Public International Law & Policy Group.