US President Donald Trump on Monday (IST) said he was "not happy" with Russia's recent large-scale strike against Ukraine, adding that he was "absolutely" considering new sanctions against Moscow.

Speaking to reporters in New Jersey, Trump criticised Russian President Vladimir Putin and accused him of "killing a lot of people" in the attack, Bloomberg reported.

Trump noted, "I'm not happy with what Putin is doing. He's killing a lot of people, and I don't know what the hell happened to Putin."

He further added, "I've known him a long time, always gotten along with him, but he's sending rockets into cities and killing people, and I don't like it at all."

In a post shared on his private social media platform Truth Social, Trump said that Putin “has gone absolutely crazy".

Trump made these remarks after Russia launched a massive drone-and-missile attack in Ukraine's capital, Kyiv, which resulted in the death of at least 12 civilians and left nearly a dozen injured. According to an Associated Press report, Ukraine was hit with 367 drones and missiles, making it the largest single attack of the over three-year-long war.

“I’ve always said that he wants all of Ukraine, not just a piece of it, and maybe that’s proving to be right, but if he does, it will lead to the downfall of Russia," said Trump in his post.