UKRAINE could be granted permission to fire Western missiles deep into Russian territory within days.
Sir Keir Starmer will discuss the matter with Joe Biden at a hastily arranged White House summit on Friday.
The US President had previously shunned Ukrainian hero Volodymyr Zelensky’s pleas to use long range weapons to turn the war with Russia.
But US Secretary of State Antony Blinken will this week travel to Kyiv to “look and listen” over the issue alongside his British counterpart David Lammy.
He said the United States were “not ruling out” permission to fire UK provided Storm Shadow missiles at Russian supply lines and airfields used to bombard Ukraine.
The pair told a London press conference on Tuesday their joint visit would be critical in order to allow both men to listen to Ukrainian concerns and report back to their leaders.
“It’s hugely important that we’re travelling together to hear from our Ukrainian counterparts and President Zelensky, their assessment of the situation on the ground and their needs on the ground,” Mr Lanmy added.
Mr Blinken said the UK and the US would “look and listen” to Ukraine’s request to lift restrictions on firing at Russia – which risks the wrath of Putin.
They will report back to Joe Biden and Sir Keir Starmer who are due to meet in Washington on Friday to discuss the matter.
The movement came after Ukraine blitzed Moscow with its biggest ever drone attack.
At least 140 large, plane-sized flying bombs sparked panic and chaos in the Russian capital.
Many were downed but several penetrated defences and one woman was killed when an apartment block was hit.
Russia’s defence ministry claimed to have “intercepted and destroyed” 144 of the drones but conceded that some got through, hitting apartment blocks and starting fires.
Meanwhile Iran Air has been banned from flying over or landing in Britain in retaliation for Tehran selling Russia cruise missiles.
The sanctions slap came after Foreign Secretary David Lammy accused mad mullahs of a “dangerous escalation”.