LONDON — Russia targeted Ukraine with a “massive” aerial attack, including waves of drones, launching so many of them that “there was not a single hour when our skies were clear” for most of Wednesday and into Thursday morning, President Volodymyr Zelenskyy said.

Hundreds of attack drones were fired between midnight and 9 a.m. local time on Thursday, the president said.

“It is obvious that Russia deliberately chose to escalate its attacks after receiving sanctions relief and seeing attempts to pressure Ukraine,” Zelenskyy said. “Russia exploits every such opportunity and must be held accountable for what it does.”

The overnight attack followed Ukrainian officials saying this week that the U.S. government-owned Starshield satellite infrastructure used by Ukraine’s military for drone navigation and air defense was not operating at its normal functionality.

Those systems are used in part for early warnings when Russia launches a projectile.

“Strong decisions are needed to end this war. Ukraine needs steady support, above all in defending our skies,” Zelenskyy said on Thursday. “We need HONESTY from our partners about this war: It is important that everyone in America stand not with the aggressor, but with our efforts to protect lives, end this war, and guarantee security.”

President Donald Trump had said in a statement on Sunday that both sides had agreed to an “energy ceasefire.” Russia in the following days continued striking energy infrastructure throughout Ukraine, according to Kyiv.

Russia’s Ministery of Defense on Thursday said Ukraine had also resumed its strikes on energy infrastructure, saying that Kyiv had overnight “attempted a massive attack on the oil refinery in Ryazan.”