Croatian Flash offensive from May 1, 1995, is marked differently on two sides of the border between former republics of the same country: while the Croats celebrate the beginning of the liberation of the territory held by rebel Serbs, the Serbs commemorate their victims.

Clergy held a memorial service in the Belgrade St. Mark's church, while Croatian President Kolinda Grabar-Kitarovic and other top country's officials joined the celebration of the Operation Flash in the western Slavonia's town of Okucani.

The Croatian Army launched the operation in its western chunk of Slavonia region in 1995 and defeated the Serb forces in three days. Many locals fled the region.

The offensive came in a late stage of the Croatian War of Independence 1991-1995.

The last organised resistance of the Serbs formally ceased on May 3, with the majority of troops surrendering but mopping-up operations continued for another two weeks.

According to data of the Serb Documentation-Information Centre Veritas, 283 people were killed or went missing during the operation, mostly the Serbs. The Centre did not say how many of them were civilians.

Croatia's official data say that about 7,200 troops and police officers took part in the liberation of western Slavonia, of whom 42 were killed and 162 wounded. It was the first time during the 1991-1995 Homeland War that the Croatian Air Force had used airstrikes on a large scale, and the enemy was further surprised by tanks that were brought in by rail and deployed in combat.

“Operation Flash marked the beginning of the liberation of Croatian territory and the re-integration of Croatia,” Grabar-Kitarovic said, adding that her thoughts were with the families of all defenders who had been killed or went missing.

She was also asked to comment on Serb victims killed during Operation Flash.

“We regret every victim,” Grabar-Kitarovic replied.