Nearly half a million households were left without power on Christmas Day in frigid weather after further missile attacks by Russia on Ukraine's damaged power grid, according to multiple reports.

Russia's security agency detains four citizens after claiming it foiled a series of assassination attempts on high-ranking officials. Meanwhile, Ukraine says more Russian drones attacked after a Christmas Day offensive.

Ukraine's air force says it detected 184 missiles and drones, causing damage to energy infrastructure across the country.