US President Joe Biden approved Ukraine using US weapons to strike targets inside Russia that were attacking the Ukrainian city of Kharkiv, after Kyiv sought authorisation from Washington in recent weeks, US Secretary of State Antony Blinken confirmed on Friday.

Speaking at a news conference in Prague after an informal meeting of Nato foreign ministers, Blinken did not specifically say whether Biden’s authorisation could expand to include other Russian cities and targets deeper inside Russia.

Outgunned and outmanned on the battlefield, Kyiv has been increasing pressure on its Western allies to be able to launch offensive strikes at military targets inside Russia to better repel Russian advances.

Blinken said Washington’s move, a marked change in policy by Biden, who steadfastly refused to allow Ukraine to use American weaponry inside Russia, was a result of the US adjusting and adapting to the battleground. Now, he said, the US is responding to what it has seen in and around the Kharkiv region.

“Over the past few weeks, Ukraine came to us and asked for the authorisation to use weapons that we’re providing to defend against this aggression, including against Russian forces that are massing on the Russian side of the border and then attacking into Ukraine,” Blinken said.

“And that went right to the president, and as you’ve heard, he’s approved [the] use of our weapons for that purpose. Going forward, we’ll continue to do what we’ve been doing, which is as necessary adapt and adjust,” Blinken said.

Kharkiv, Ukraine’s second-largest city, is 30 kilometres from the border with Russia.

It is the second time this year that Biden has quietly relaxed his policy on weapons supplies for Ukraine. Earlier this year, he bent to calls to send long-range missiles known as ATACMS to Kyiv.

US officials said on Thursday that US policy would continue to prohibit the Ukrainian military from using ATACMS, which have a range of up to 300km, and other long-range US weapons for deep strikes inside Russia.

The US is the biggest supplier of weapons to Ukraine in its battle against the full-scale invasion launched by Russian President Vladimir Putin in February 2022.

“A question of time”

Ukrainian President Volodymyr Zelensky said on Friday that Ukraine using any Western weapon to strike Russian territory is “a question of time”.

“I think that using any weapon, Western kind of weapon, on the territory of Russia is a question of time. Otherwise, it is not about just peace,” Zelensky told reporters on a visit to Stockholm.

Ukraine has stressed the urgency for the use of Western-supplied arms to conduct strikes inside Russia as it defends against Russian advances in the northeastern Kharkiv region.

This spring, Ukraine found itself on the back foot in the 27-month-old full-scale invasion as it faces delays in military aid from the US, increased attacks on its energy infrastructure and Russia’s push to expand the frontline.

Zelenskiy said Ukraine “got [a] message from the American side early in the morning” which signified a “step forward” in defending people in villages near the border with Russia. He did not disclose additional details on the communication with the US.

Zelenskiy said he did not yet know the possible restrictions related to the use of long-awaited F-16 fighter jets, but appealed to the question of fairness in deliberations, saying Ukraine should be able to retaliate against Russian strikes.

Germany, another major ally, signalled its openness to Ukraine’s use of its weapons to strike military sites fuelling attacks on the Kharkiv region.

France has taken a similar stance, saying Ukraine should be allowed to strike military sites Russia is using to attack its territory.