US President Joe Biden has authorised Ukraine to launch limited strikes into Russia using US-made long-range missiles, in a big policy shift before the end of his White House term in January, two people familiar with the decision said.

The move by Biden comes in response to the deployment of thousands of North Korean troops to support Russia in its war against Ukraine, and after a barrage of new strikes by Moscow on Ukrainian cities at the weekend.

Tuesday will mark the 1,000th day of Moscow’s full-scale invasion of Ukraine.

Biden has allowed Ukraine to use HIMARS — the American High Mobility Artillery Rocket System — to strike targets inside Russia.

But he has long resisted allowing Kyiv to launch strikes within Russia using US-made long-range missiles known as the Army Tactical Missile System, or ATACMS, on the grounds that it could escalate tensions with Moscow. ATACMS missiles have a range of up to 300 kilometres, or 190 miles.

He is now dropping those objections more than two months before he leaves office to make way for Donald Trump. The Republican is sceptical of additional military aid to Ukraine and has vowed to bring a swift end to the war — without saying how exactly he would do it.

The White House declined to comment. The Pentagon declined to respond to a request for comment.

In a late-night address in Kyiv on Sunday, Ukrainian President Volodymyr Zelenskyy noted media reports “talking about the fact that we have received permission” to use the ATACMS inside Russia, though he did not confirm Biden’s decision.

Zelenskyy has pleaded for months for the US and other western partners to lift restrictions placed on long-range weapons provided by them for use inside Russia.

He has argued that cross-border strikes with the American ATACMS, British Storm Shadow and French Scalp missiles were necessary to hit Moscow’s forces before they could launch new attacks on Ukrainian targets, including critical infrastructure.

“Two countries are against us, against Ukraine,” Zelenskyy said on Friday, referring to Russia and North Korea. “We would very much like to be granted the ability to use long-range weapons against military targets on Russia’s territory.”

Andriy Zagorodnyuk, a former Ukrainian defence minister, said the use of ATACMS missiles would allow Kyiv to set its sights on “high value targets” and “potentially disrupt Russian operations”.

“There are targets which can only be addressed by high payload missiles such as ATACMS or equivalent aerial missiles. This is, of course, a decision giving Ukraine troops a chance, though as with many previous decisions coming after a significant and extremely painful delay.”

Biden’s decision to allow the Ukrainians to use ATACMS missiles followed the deployment early last month of some 12,000 North Korean troops to Russia.

This was the first foray into the war by a foreign military and a major expansion of North Korea’s support for Russia’s invasion of Ukraine.

Pyongyang had previously provided Moscow with hundreds of ballistic missiles and millions of artillery shells. In exchange, Moscow has provided Pyongyang with military technologies to help with its missile programmes and money, a senior Ukrainian official said.

In recent weeks, Moscow has massed some 50,000 troops, including 10,000 North Korean soldiers, ahead of an anticipated offensive in Russia’s Kursk region to retake about 600 sq km of territory held by Ukrainian forces since their incursion in August.

The American ATACMS missiles are likely to be first used by Ukraine to target those Russian and North Korean forces in the Kursk region. 

A Ukrainian intelligence assessment shared with the Financial Times revealed that North Korea has supplied Russia with long-range rocket and artillery weapons, including 50 domestically made 170mm M1989 self-propelled howitzers and 20 updated 240mm multiple launch rocket systems.

Some of these weapons have been moved to the Kursk region for the planned assault involving North Korean troops.

“Even if limited to the Kursk region, ATACMS missiles put at risk high value Russian systems, assembly areas, logistics, command and control,” said Michael Kofman, senior fellow at the Carnegie Endowment for International Peace.

“They may enable Ukraine to hold on to Kursk for longer and raise the costs to North Korea for its involvement in the war.”

Bill Taylor, former US ambassador to Ukraine, said Biden’s decision makes “Ukraine stronger and increases the odds of a just end to the war”.

“The decision may also unlock British and French missiles. Possibly even German,” he added.

When asked about the escalatory risk from the US shift in policy, António Guterres, UN secretary-general, told reporters at the G20 in Rio de Janeiro: “We have a very consistent position regarding escalation in the Ukrainian war. We want peace . . . in line with the UN charter and international law.”

Russia has not yet responded to the move. In September, Vladimir Putin said any such US authorisation would mean “the direct involvement of Nato countries, the US, and the EU . . . It would mean they are at war with Russia — and if that’s the case, we will make the corresponding decisions.”

Russian military bloggers close to the Kremlin responded on Telegram with fury and frustration to the news.

Rybar, a channel with more than 1.3mn subscribers, said the threat of ATACMS missiles would force Russian command and control centres, air defences and airfields further from the front lines. 

Additional reporting by Henry Foy and Anastasia Stognei