Air strike sirens resounded in some parts of Belgrade Monday during a NATO meeting hosted by the Serbian capital.
Although not a member of the Alliance, Serbia agreed to host the meeting to stress its desire for rapprochement and integration.
The fact of the meeting has provoked the ire of parts of the Serbian population, 61% of whom are against NATO membership.
In 1999 NATO staged air strikes against Belgrade and other Serbian cities, including on civilian targets.
At the same time, the first Bulgarian-US-Serbian military drills started Monday near Novo Selo in Bulgaria.