Russia's defense ministry said on Friday that its forces used Oreshnik hypersonic missiles to strike "strategic targets" in Ukraine overnight. The ministry gave no details on exact locations or damage but said the strike was retaliation for a December drone attack Russia claimed targeted President Vladimir Putin's residence. Ukraine denied any involvement. Ukraine's foreign minister said the Oreshnik missile landed close to the EU and NATO border, calling it a "grave threat" to European security and a 'test' for Kyiv's allies. Kyiv reported Russia launched 36 missiles and 242 drones overnight. This massive attack burned apartment blocks and killed at least four people in Kyiv. Additionally, Ukraine struck Russia’s Belgorod region, cutting heat and electricity for over 556,000 people, Governor Vyacheslav Gladkov said. Temperatures remained near freezing, worsening the impact. Kyiv officials said the missile and drone onslaught also targeted the western city of Lviv. Kyiv Mayor Andriy Sadoviy mentioned an unknown ballistic missile was used. Among the four killed was an emergency medical worker, according to Tymur Tkachenko, head of Kyiv's military administration. Five rescue workers were injured while responding to the attacks. Multiple districts in Kyiv were hit. In Desnyanskyi district, a drone crashed on a roof, and a residential building’s first two floors were damaged. In Dnipro district, drone debris triggered a fire in a multi-storey building. Mayor Vitali Klitschko said water and electricity were disrupted in parts of Kyiv. The attack came hours after President Volodymyr Zelenskyy warned that Russia plans a major offensive, using freezing weather to their advantage. Roads and icy streets threaten emergency efforts and city movement.