United States President Joe Biden has eased a ban on Ukraine using US weapons inside Russian territory to help the country defend its northeastern Kharkiv region from attack, Secretary of State Antony Blinken has confirmed.

Speaking at a news conference in Prague after an informal meeting of NATO ministers on Friday, Blinken said that Biden’s approval came after Kyiv sought authorisation from Washington in recent weeks.

“And that went right to the president, and as you’ve heard, he’s approved 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 added.

He also noted that Washington’s move marked a change in policy by Biden, who had previously refused to allow Ukraine to use American weaponry for strikes inside Russia.

Blinken added that the US is responding to what it has seen in the Kharkiv region, which has come under renewed Russian attacks in Recent weeks.

Kharkiv, Ukraine’s second largest city, is 19 miles (30 km) 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 agreed to send long-range missiles, known as ATACMS, to Kyiv.

The US decision this week angered Kremlin officials. It came as France and other European countries also indicated that Ukraine would be allowed to use their weapons on military targets inside Russia.

Russian President Vladimir Putin had warned on Tuesday of “serious consequences”, stressing his country’s nuclear strength, if Ukraine’s Western allies loosened their policy.

Russia’s RIA Novosti agency quoted Andrei Kartapolov, the head of the Russian lower house’s defence committee, as saying on Friday that Moscow will retaliate asymmetrically to Ukrainian attacks on its territory using weapons provided by the US.

Senior Russian security official Dmitry Medvedev also said Russia was not bluffing when it spoke of the possibility of using tactical nuclear weapons against Ukraine and that its conflict with the West could escalate into an all-out war.

Germany on Friday also suggested Ukraine could use weapons supplied by Western countries to strike forces inside Russia.

Germany discussed with allies that Russia has carried out strikes on the Kharkiv region from positions in the immediately adjacent Russian border area, a government spokesperson said in a statement.

“We are jointly convinced that Ukraine has the right, guaranteed under international law, to defend itself against these attacks,” the spokesperson said. “It can also use the weapons supplied for this purpose in accordance with its international legal obligations; including those supplied by us.”

‘It’s the right move’

Ukrainian President Volodymyr Zelenskyy has been urging Kyiv’s allies to allow it to use their longer-range weaponry to hit targets on Russian soil amid a surge in attacks this month, particularly on Kharkiv.

A Russian attack at midnight (21:00 GMT) killed at least three people and injured 16 after a Russian missile hit an apartment block in the city. Last weekend, 19 were killed after a Russian attack on a hardware superstore.

“The Biden administration has come a long way from their hypersensitivity to and misunderstanding of the risk of escalation,” Alexander Vindman, a retired army lieutenant colonel and former director for European affairs at the White House National Security Council, told Reuters.

He applauded the shift in Biden’s policy, which he said “unties Ukraine’s hands”.

“Of course, it’s the right move,” Vindman said.

David Des Roches, a US defence policy specialist at the Near East South Asia Center for Security Studies, said the Biden administration has shown a pattern of initially denying Ukraine’s request and eventually giving in due to the realities on the ground.

“There’s another dynamic here,” he told Al Jazeera. “The Ukrainians with their own weapons have been attacking Russia’s nuclear infrastructure. They just damaged the Krasnodar early warning radar with a domestically produced drone; that’s very far within Russia.

“Early on this year, they attacked the strategic [Engels] bombing base … Paradoxically, allowing Ukraine to strike within Russia within this limited tactical operation – the price for that is the cessation of Ukrainian strikes on the strategic capabilities of Russia.”

The US is the biggest supplier of weapons to Ukraine in its battle to push back the Russian military, which began a full-scale invasion of the country in February 2022.

The Biden decision came shortly after NATO chief Jens Stoltenberg told the alliance’s foreign ministers that the “time had come” to relax the restrictions placed on Kyiv over the use of the weapons and “enable Ukrainians to really defend themselves”.