Three sources familiar with the matter told Reuters.
The decision implies a significant change in US policy in the conflict between Ukraine and Russia.
Ukraine plans to carry out its first strikes against targets in Russia in the coming days, the sources said, without disclosing details due to operational security concerns.
The White House refuses to comment on the matter.
The US’s change of course comes just over two months before the newly elected President Donald Trump takes office on 20 January. Ukrainian President Volodymyr Zelenskyy has been asking for months for the Ukrainian military to be allowed to use American weapons to attack Russian military targets far from the country’s border.
The decision comes after Russia deployed North Korean ground forces to supplement its own forces, a development that has caused unease in Washington and Kyiv.
The first deep attacks are likely to be carried out using ATACMS missiles, which have a range of up to 306 km, according to the sources.
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