As at this time, Abkhazia, Kosovo, Transnistria, Somaliland, South
Ossetia and others are not in the ISO 3166-1 standard, so ICANN is not
in a position to grant any corresponding country-code domain for them.
By strictly adhering to the ISO 3166-1 standard, we ensure that ICANN
remains neutral by relying upon a widely recognised and impartial
The previous writers have already mention the fact that ISO only "copies" the country lists of the UN, to avoid poltical trouble.
As an Albanian from Kosovo I'm following this kind of discussions for years.
There are 3 criteria for inclusion into ISO 3166-1 and Kosovo meets two of them:
A member of one of its specialized agencies (International Monetary Fund and the World Bank Group)
A party to the Statute of the International Court of Justice ( It is now)