The leaders were not expected to meet with President Trump on Saturday in any case, though Trump had inaugurated the process last year by dangling the possibility of a White House peace summit.
The Hague-based special prosecutor’s office has been investigating crimes against ethnic Serbs connected to Kosovo’s 1998-1999 war of independence.
Many of Kosovo’s leading politicians took part in the war, which claimed more than 10,000 lives and ended after a 78-day NATO bombing campaign in support of the separatists.
Thaci was one of the top commanders of the Kosovo Liberation Army and has denied previous allegations of war crimes.
The special prosecutor’s office said Wednesday that based on a “lengthy investigation,” it could prove “beyond a reasonable doubt” that Thaci and others had perpetrated “murder, enforced disappearance of persons, persecution, and torture.” It added that “the crimes alleged in the indictment involve hundreds of known victims of Kosovo Albanian, Serb, Roma, and other ethnicities and include political opponents.”
The indictment must still be approved by a judge before any legal process goes forward.
Thaci did not immediately comment on the substance of the charges, beyond the announcement that he would return to Kosovo. A spokesman did not respond to a request for comment.
The Trump administration also did not comment on the substance of the indictment beyond Grenell’s tweet.
Thaci was expected to visit the White House along with Serbian President Aleksandar Vucic on Saturday. Serbia never recognized Kosovo’s 2008 declaration of independence, and the summit was intended to try to resolve their impasse. NATO peacekeepers are still deployed within Kosovo.
If the talks do go forward, Thaci’s absence will be felt. Hoti, the prime minister, has been in office for only three weeks, whereas Thaci has led Kosovo as prime minister or president for most of its independent existence.
Grenell, who recently stepped down as the U.S. ambassador to Germany and as acting director of national intelligence, helped broker the White House meeting between the Serbian and Kosovar officials.
Under Trump, the United States has expressed openness to resolving the dispute through land swaps between Kosovo and Serbia — though many European leaders fear that could reignite the conflict by reopening some of the core issues that caused the 1998 war in the first place.
The European Union has long taken the lead in trying to resolve the situation, which it says is an important first step for Serbia’s and Kosovo’s potential entry into the bloc. And European leaders complained that Grenell had not consulted with them when setting up the White House meeting.
Grenell has denied that the United States and Europe were in conflict. He said the U.S. conversation would focus on economic issues, while the E.U. continued to pursue political issues. He said land swaps would not be discussed at Saturday’s meeting.
The prosecutor’s office said the indictment was filed April 24 for approval by a pretrial judge that was supposed to be completed within six months. Ordinarily, the allegations would have remained secret for the time being, but the office said it was publicizing them now because of repeated efforts by Thaci and others “to obstruct and undermine the work” of the special court.
Kadri Veseli, another former Kosovo Liberation Army commander and a former speaker of Kosovo’s parliament, was also named in the announcement of the indictment. He has denied past allegations of war crimes.
The court is ruled by Kosovar law but is staffed and funded by the E.U. Last year, Kosovar Prime Minister Ramush Haradinaj resigned abruptly after being called for questioning by the same court.
Investigators have in the past accused Kosovo Liberation Army forces of harvesting the organs of prisoners and of murdering Serbs and ethnic Albanians suspected of collaboration with the Serbian state.