Russia launched a rare drone and missile attack on western Ukraine overnight, officials said Thursday, striking targets including an American-owned electronics plant and injecting further uncertainty into the U.S.-led efforts to end the 3-year-old war, Associated Press reported.

The aerial assault on a part of Ukraine that has largely not experienced such focused attacks was one of Russia’s biggest this year and came as Moscow objects to key aspects of proposals that could end the fighting.

U.S. President Donald Trump discussed the war with Russian President Vladimir Putin in Alaskalast week before hosting Ukrainian President Volodymyr Zelenskyy and European leaders at the White House on Monday, according to Associated Press.