Russia fired more than 620 drones and long-range missiles overnight, killing at least six people in the latest wave of strikes, Ukraine said Saturday, adding that it was close to an agreement to receive more Patriot air-defense systems.

"The Russians continue to use their specific tactics of terror against our country, striking concentrated blows at one city or another, at one region or another," Ukrainian President Volodymyr Zelenskyy said in his evening address.

Moscow has stepped up aerial strikes over recent months as U.S.-led ceasefire talks have stalled.