The move comes as Joe Biden heads into his final months in US office, with successor Donald Trump believed to be more favourable towards Russia.
Outgoing United States President Joe Biden will allow Ukraine to use US-provided weapons to strike inside Russia, various news outlets, including Reuters, the Associated Press and the New York Times, have reported.
Three sources, familiar with the matter, including two US officials, told Reuters on Sunday that Ukraine plans to carry out long-range attacks using the weapons in the coming days.
The White House has not commented on the reports, but Ukrainian President Volodymyr Zelenskyy said that the missiles would “speak for themselves”.
“Today, many in the media are saying that we have received permission to take appropriate actions,” Zelenskyy said in his evening address to Ukrainians. “But strikes are not made with words. Such things are not announced. The missiles will speak for themselves.”
The Polish Foreign Minister Radoslaw Sikorski welcomed the reports, saying that the US was responding to Russia in “a language that [Russian President Vladimir] Putin understands”.
Vladimir Dzhabarov, a Russian lawmaker, said that allowing Ukraine to strike inside Russia with US-supplied missiles would lead to a third world war, according to state news agency TASS. The lawmaker added that the Russian response would be immediate.
The move by Biden comes as he prepares to leave office in two months, with President-elect Donald Trump taking office on January 20.
Trump and members of his incoming administration have indicated that they are more sceptical of heavily supporting Ukraine in its war against Russia, and it is unclear whether Trump will reverse the decision to allow Ukraine to use the US-supplied weapons inside Russia.
The Republican leader has promised to end the war quickly, but has not given details as to how he would go about doing so.
Ukraine is expected to use US-made Army Tactical Missile Systems (ATACMS) rockets, which have a range of up to 190 miles (306km), the sources told Reuters, as Kyiv takes advantage of a still-friendly US administration. Zelenskyy had been pressing for months for permission to use the weapons against targets deep inside Russian territory.
Moscow has warned that it would see any move by Washington to loosen restrictions on the use of US-supplied weapons as a major escalation.
The US decision marks a significant shift in policy, and boosts a Ukrainian government that has struggled to stop Russian attacks on cities and its electrical grid.
Biden had long opposed moves to use US weapons against Russia, however, fearing that it would drag the US and its NATO allies into direct conflict with Russia.
But the president appears to have relented, after momentum in the war shifted towards Russia. North Korea has deployed thousands of soldiers to support Russia as it attempts to regain territory in Kursk lost to Ukraine.
And Moscow believes that Trump will likely be a more favourable negotiator, and one who could force Kyiv to give up territory Russia currently controls in eastern and southern Ukraine.