On March 15, 2025, during a 15-minute silence at Serbia’s largest protest in history, video captured something strange. Part of the crowd in central Belgrade suddenly split and ran in panic. Some witnesses described a terrifying, fast-moving sound.

Within days, Serbian NGOs said they had collected around 500 citizen reports of a powerful noise followed by physical and psychological symptoms. Many pointed to a Long Range Acoustic Device (LRAD), often called a sound cannon, which is illegal in Serbia.

The government’s account shifted. Officials first denied owning any such device. After photos surfaced of an LRAD mounted on a vehicle near parliament, the Interior Ministry admitted it had one but insisted it was used only for warnings, never against the crowd. President Aleksandar Vucic called the accusations a foreign-backed plot and invited both Russia’s FSB and the FBI to investigate.

The European Court of Human Rights demanded answers from Serbia within a week. In April 2025 it ordered interim measures to stop any future use of sound devices for crowd control. Prosecutors opened a case but have offered no other explanation for what scattered the crowd. A Belgrade security researcher said it was highly probable that some unconventional weapon had been used.