President Trump said the Russian leader Vladimir Putin had warned that he would retaliate for a covert Ukrainian attack in Russia last weekend that destroyed dozens of Russian bombers.

At least three were killed and 49 injured in a missile-and-drone attack that focused on Kyiv, days after a daring assault on Moscow’s bomber fleet.

Russia launched large-scale drone and missile strikes on Ukraine's capital and other parts of the country early on Friday, local officials said. At least four people were killed in Kyiv and at least 20 have been injured, the city's mayor Vitaliy Klitschko said.