Russia has accused Ukraine of attempting to assassinate President Vladimir Putin by launching two drones towards the Kremlin in Moscow.
The drones were reportedly disabled using electronic radar assets, and footage on social media appeared to show an object flying over the Kremlin before a small explosion.
However, Ukraine has denied any involvement in the drone strike and said it was focusing on liberating its own territory after Russia invaded last year.
The incident has raised concerns that Russia may be preparing a large-scale terrorist provocation in Ukraine. No one was hurt in the attack and there was no damage to buildings, but fragments of the drones had fallen on the Kremlin site.
The Victory Day parade in Russia is expected to go ahead as planned, despite the incident.