Kyiv (AFP) — United States President Donald Trump threatened Sunday to impose more sanctions on Russia, after the Kremlin unleashed its biggest-ever aerial barrage at Ukraine.

Russian missiles and drones rained down across Ukraine early Sunday, killing four people and setting government offices in the capital Kyiv ablaze.

Trump told reporters after the assault he was “not happy with the whole situation” and said he was prepared to move forward on new sanctions on Moscow.

Ukrainian President Volodymyr Zelensky said he was counting on a “strong” US response.

Russia has intensified its onslaught against Ukraine since a meeting between Trump and President Vladimir Putin on 15 August failed to make any breakthrough on a ceasefire.

After Sunday’s attack on Kyiv, flames could be seen rising from the roof of the sprawling government complex that houses Ukraine’s cabinet of ministers in the heart of the city — the first time it has been hit during the three-and-a-half-year conflict.