President Donald Trump told journalists that he was "not happy" with Russia's recent large-scale strike against Ukraine while speaking to the press on Sunday. Speaking to reporters at Morristown Municipal Airport in New Jersey, Trump accused Putin of "killing a lot of people" in the attack, which was launched on Sunday afternoon. "I'm not happy with what Putin is doing," Trump explained. "He's killing a lot of people, and I don't know what the hell happened to Putin." "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," he added. FEDERAL JUDGE BLOCKS TRUMP ADMINISTRATION FROM TERMINATING INTERNATIONAL STUDENTS' LEGAL STATUS Trump said that Putin was "shooting rockets into Kyiv and other cities" in the middle of negotiations. "I don't like what Putin is doing. Not even a little bit," the president emphasized. "He's killing people. And something happened to this guy." Trump's comments came after Russian forces launched hundreds of drones and missiles at Ukrainian cities overnight. The attack, which has been called the largest aerial attack of the war so far, targeted the Ukrainian capital of Kyiv. TRUMP ADMINISTRATION BEGINS NEW WAVE OF INTERNATIONAL STUDENT VISA REVOCATIONS: ‘NO ONE HAS A RIGHT TO A VISA' Ukrainian officials said that at least 12 people were killed and dozens more were injured. Though past strikes have proven more deadly, the attack is the largest-scale aerial assault of the war in terms of the number of weapons: 298 drones and 69 missiles were launched. In a post on Telegram, Ukrainian President Volodymyr Zelenskyy called for an international response to the attack. CLICK HERE TO GET THE FOX NEWS APP "The silence of America, the silence of others in the world only encourages Putin," he wrote on Telegram. "Every such terrorist Russian strike is reason enough for new sanctions against Russia." Reuters and Fox News Digital's Brooke Curto and Kyle Schmidbauer contributed to this report.