The move follows months of requests by Ukrainian President Volodymyr Zelenskyy to permit the nation's military to use US weapons to hit Russian military targets far from its border.
United States President Joe Biden's administration has allowed Ukraine to use US-made weapons to strike deep into Russia, two US officials and a source familiar with the decision say.
It is a significant reversal of US policy in the Ukraine-Russia conflict.
Ukraine plans to conduct its first long-range attacks in the coming days, the sources said, without revealing details due to operational security concerns.