Russian attacks on nine regions of Ukraine caused emergency power outages for hundreds of thousands of households and damaged numerous homes, wounding at least 15 people, officials said Friday, as civilian casualties from Moscow's invasion climb steeply.

The latest aerial strikes on civilian targets came as fears mount that a sharp deterioration in relations between Kyiv and Washington this week could leave Ukraine further exposed to Russia's escalating aerial assaults as the bitter winter approaches.

Russia's heavy bombardment of the power grid before winter sets in has been an annual feature of the war, aiming to wear down Ukraine's appetite for the fight by denying civilians heating and running water.