Russia accused Ukraine of launching drones at the Kremlin aimed at killing President Vladimir V. Putin.
The Ukrainian president denied the claim, and officials in Kyiv warned that Russia could use it to launch "a large-scale terrorist provocation." Russian presidential office said defenses downed two drones overnight.
Putin's spokesman said the Russian leader had not been in the complex at the time.
The Russian leader was unhurt and his schedule would continue as normal, his office said. He was working in Novo Ogaryovo outside Moscow.
Unverified footage on social media appeared to show an object flying over the Kremlin before a small explosion.
Ukraine's President Volodymyr Zelensky denied his country was behind it.
Fragments of the drones had fallen on the Kremlin site but no one had been hurt and there was no damage to buildings, the presidency said.
It also noted the incident had come shortly before Russia's 9 May Victory Day parade, which foreign dignitaries were expected to attend
Source: Kuwait News Agency