A major Russian counter offensive is expected there within days, assisted by as many as 10,000 troops from North Korea.
Use of the missiles, capable of targeting military facilities deep inside Russia, could complicate Russia’s efforts, enabling Ukraine to hold onto this valuable bargaining chip ahead of any possible peace talks next year.
Ukrainian military experts have welcomed Washington’s decision – saying it will not necessarily change the course of the war, but will restore a little balance.
This comes at a time when Russian forces are creeping forward all along the eastern front and Ukraine feels it has been on the back foot for several months.
“Ukrainians are very much inspired with the news,” said Maj Volodymyr Omelyan from the Brigade of Armed Forces of Ukraine.
Putin has previously warned that such a move from the US would amount to direct participation of Nato countries in the war – but Maj Omelyan said this was simply “bluffing”.
“We shall not pay any attention,” he told the BBC World Service, since Russia had issued similar warnings about “many other systems and weapons we received”.
“Nothing happened. Nothing will happen this time as well.”
The former government minister added that Ukraine needed similar permission for the use of Storm Shadow missiles, manufactured by Britain and France.
Ukrainian MP Inna Sovsun said Ukrainians were “happy this decision has been taken” and that it would make a “huge difference”.
But she said there was discontent “that it took Biden so long to make a decision that could have saved lives” had it been taken earlier.
“I wish it [had] been made before Putin had destroyed half of Ukraine’s energy infrastructure,” she said.
What we do not know are the specifics of Washington’s decision. We do not know how many of the systems Ukraine has.
Oleksiy Goncharenko, an MP for Odessa, stressed that Ukraine needed a sufficient quantity of missiles for Washington’s move to matter.
“It’s very important to have not just permission but missiles – to be capable… to make a difference to the situation.”
He added that it was a “pity” the decision “took almost 1,000 days”, adding that it was “better late than never”.
We do not know what the Americans are saying in terms of what Ukraine can and cannot do with the missiles. We will also have to see whether Ukraine is allowed to use the missiles more widely in the future
But another Ukrainian MP, Maria Ionova stressed that missiles were “not the silver bullet”.
She said the focus needed to be on a change in strategy.
“Because our enemies are united – and we should stand together as well.”
It is a significant move ahead of another long hard winter.
But Sunday’s Russian missile and drone attacks, which killed as many as 20 people, served as a stark reminder that Moscow is still intent on winning the war, on its terms.