President Joe Biden has for the first time authorised Ukraines use of US-supplied long-range missiles to strike deep inside Russia, according to three sources familiar with the matter.
The decision is a major US policy shift and comes as Biden is about to leave office and President-elect Donald Trump has pledged to limit American support for Ukraine and end the war as soon as possible.
The weapons are likely to be used in response to North Koreas decision to send thousands of troops to Russia in support of Russian President Vladimir Putins invasion of Ukraine, according to one of the sources.
Ukraine plans to conduct its first long-range attacks in the coming days, the sources said, without revealing details due to operational security concerns.
The first deep strikes are reportedly likely to be carried out using ATACMS rockets, which have a range of up to 190 miles.
Biden allowing Volodymyr Zelenskys forces to use US-supplied missiles for strikes deep into Russia has raised expectations for the UK to follow suit with its Storm Shadow missiles.
Keir Starmer has previously said that he would be in favour of giving the green light for the Storm Shadow missiles to be used.
His French counterpart Emmanuel Macron echoed this sentiment, which might mean that France could soon allow Ukraine to fire their supplied long-range missiles into Russia.
US President Joe Biden shakes hands with Ukrainian President Volodymyr Zelensky in September
Zelensky has long asked for permission to use the long-range missiles to hit Russian supply lines, airbases and command-centres to get an advantage over Putins forces.
While some US officials have expressed skepticism that allowing long-range strikes will change the wars overall trajectory, the decision could help Ukraine at a moment when Russian forces are making gains and possibly put Kyiv in a better negotiating position when and if ceasefire talks happen.
It is not clear if Trump will reverse Bidens decision when he takes office. Trump has long criticized the scale of US financial and military aid to Ukraine and has vowed to end the war quickly, without explaining how.
Still, some congressional Republicans have urged Biden to loosen the rules on how Ukraine can use US-provided weapons.
Russia has warned that it would see a move to loosen the limits on Ukraines use of US weapons as a major escalation.