Ukraine has deployed more American-made Patriot air defense systems to strengthen its defenses against Russia’s relentless aerial assaults, President Volodymyr Zelenskyy announced Monday, as Russian drone attacks overnight killed one man and wounded five members of his family, including two children.

Russia's relentless pounding of urban areas behind the front line following its full-scale invasion of Ukraine nearly four years ago has killed thousands of civilians. It has also targeted the energy supply to deny civilians heat and running water in winter, as well as disrupt industrial production of Ukraine's newly developed drones and missiles.

The sophisticated Patriot systems are the most effective weapon against Russian missiles. Zelenskyy has pleaded with Western partners to provide more of them, but production limitations and the need to maintain stockpiles have slowed their delivery.

"More Patriots are now in Ukraine and being put into operation," Zelenskyy said on social media late Sunday. "Of course, more systems are needed to protect key infrastructure sites and our cities across the entire territory of our state."

He thanked Germany and its Chancellor Friedrich Merz for the Patriots. Germany said three months ago it would deliver two more Patriot air defense systems to Ukraine. It agreed to the move after securing assurances that the U.S. will prioritize the delivery of new Patriots to Germany to backfill its stocks. Patriot systems are made only in the U.S.