US President Joe Biden’s administration has allowed Ukraine to use American-made weapons to strike deep into Russia, two US officials and a source familiar with the decision say.

It is a significant reversal of Washington’s policy in nearly three years of the Ukraine-Russia conflict.

Ukraine planned to conduct its first long-range attacks in coming days, the sources said, without revealing details due to operational security concerns.

The move comes two months before president-elect Donald Trump takes office on January 20 and follows months of pleas by Ukrainian President Volodymyr Zelensky to allow his military to use US weapons to hit Russian military targets far from its border.

The change was largely in response to Russia’s deployment of North Korean ground troops to supplement its own forces, a development that has caused alarm in Washington and Kyiv, a US official and a source familiar with the decision said.

Zelensky said in his Sunday night address that the missiles would “speak for themselves”.

“Today, many in the media are saying that we have received permission to take appropriate actions,” he said.

“But strikes are not made with words. Such things are not announced.”

The White House and US State Department declined to comment.

Russia has warned it would consider any move to loosen the limits on Ukraine’s use of US weapons as a major escalation.

Washington’s decision to let Ukraine strike deep into Russia with long-range US missiles could lead to World War III and would receive a swift response, Vladimir Dzhabarov, first deputy head of the Russian upper house’s international affairs committee, said, according to the TASS news agency.

Andrei Klishas, a senior member of Russia’s upper chamber of parliament, said it was “such a level of escalation that it could end with the Ukrainian statehood in complete ruins by morning”.

Ukraine’s first deep strikes are likely to be with ATACMS rockets, which have a range of up to 306 kilometres, according to the sources.

While some US officials have expressed scepticism that allowing long-range strikes will change the war’s overall trajectory, the decision could help Ukraine at a moment when Russian forces are making gains and possibly put Kyiv in a better negotiating position when and if ceasefire talks happen.

It is not clear if Trump will reverse Biden’s decision when he takes office. Trump has long criticised the scale of US financial and military aid to Ukraine and has vowed to end the war quickly, without explaining how.

A Trump spokesperson did not immediately respond to a request for comment. But one of Trump’s closest foreign policy advisers, Richard Grenell, criticised the decision.

“Escalating the wars before he leaves office,” Grenell said, in a social media post responding to the news.

No one anticipated that Joe Biden would ESCALATE the war in Ukraine during the transition period.

This is as if he is launching a whole new war.

Everything has changed now – all previous calculations are null and void. And all for politics. https://t.co/7ktLb5jpO7

— Richard Grenell (@RichardGrenell) November 17, 2024

The US believes more than 10,000 North Korean soldiers have been sent to eastern Russia and most have moved to the Kursk region and begun to engage in combat operations.

Russia is advancing at its fastest rate since 2022 despite taking heavy losses. Ukraine said it had clashed with some of the North Koreans deployed to Kursk.

Stretched by personnel shortages, Ukrainian forces have lost some of the ground they captured in an August incursion into Kursk that Zelensky said could serve as a bargaining chip.

“Removing targeting restrictions will allow the Ukrainians to stop fighting with one hand tied behind their back,” Alex Plitsas, senior non-resident fellow at the Atlantic Council, said.

“However, like everything else, I believe history will say the decision came way too late. Just like the ATACMS, HIMARS, Bradley Fighting Vehicles, Abrams Tanks and F-16. They were all needed much sooner,” he said.

Poland’s foreign minister Radoslaw Sikorski called the US move a response to North Korea’s involvement.

“President Biden responded to the entry of North Korean troops into the war and the massive Russian missile strike in a language that V. Putin understands – by removing restrictions on Ukraine’s use of Western missiles,” Sikorski said on social media platform X.