BELGRADE, Serbia (AP) — Serbia denounced Israel on Monday because its military jets and envoys took part in a ceremony in Croatia marking a victorious 1995 offensive against rebel Serb-held territories.

Foreign Minister Ivica Dacic told a private Belgrade television station that “it’s sad that an Israeli flag flew yesterday at the celebration of that criminal action.” He added that “we are very disappointed.”

He said it is “immoral” that Israel took part in the commemoration when tens of thousands of Jews, as well as Serbs and Gypsies, perished in Croatian Nazi-run death camps during World War II.

Serbia considers Israel its close ally with a common history of suffering of their peoples during the war.

Three Israeli Air Force F-16s took part in a flyby during Sunday’s ceremony marking the anniversary of the operation that restored Croatia’s control over land held by rebel Serbs during the 1991-95 war. Serbian officials have compared the attack known as Operation Storm to the policies of Nazi Germany.

A statement from the Israeli Embassy in Belgrade said that the participation of Israeli jets was related “solely” to the announced purchase of 12 Israeli F-16s by Croatia.

“This has no political elements or any connection to the historic relations between Serbia and Croatia,” the statement said. “The solid friendship that exists between Israel and Serbia will never be jeopardized in any way.”

Even before the flyby on Sunday, top Nazi hunter Efraim Zuroff criticized the appearance of Israeli jets at the ceremonies in Croatia.

“Very upset that Israeli Air Force jets will be flying in event to mark ‘Operation Storm’ during which Croatia expelled 250,000 Serbs from their homes in Croatia,” Zuroff tweeted . “Until today no foreign country has ever participated!!”