“And this is the answer to everyone who tried to achieve something with Putin through talks, phone calls, hugs and appeasement,” Zelensky said.

The comment appeared to be a dig at German Chancellor Olaf Scholz, who spoke on Friday with Putin in the first such call with a sitting head of a major Western power in nearly two years.

In Mykolaiv, as a result of a drone attack, two people were killed and six others were injured, including two children. Two more people were killed in the Odesa region, where the attack damaged energy infrastructure and disrupted power and water supplies, said Oleh Kiper, the local governor. Both victims were employees of Ukraine’s state-owned power grid operator, Ukrenergo, the company said hours later.

The combined drone and missile attack was the most powerful in three months, said the head of Kyiv’s City Military Administration, Serhii Popko.

Biden’s decision to allow Ukraine to use US-supplied weapons deeper inside Russia follows months of requests by Zelensky to allow Ukraine’s military to hit Russian military targets far from its border.

The change follows Russia’s deployment of North Korean ground troops to supplement its own forces, a development that has caused alarm in Washington and Kyiv.

The first deep strikes are likely to be carried out using ATACMS rockets, which have a range of up to 306 kilometres, sources say.

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

Some Ukraine supporters have argued that the US constraints on long-range weapons could cost Ukraine the war. The debate has become a source of disagreement among Ukraine’s NATO allies.

Biden had remained opposed, determined to hold the line against any escalation that he felt could draw the US and other NATO members into direct conflict with Russia.

It is not clear if President-elect Donald Trump, who takes office on January 20, will reverse Biden’s decision. 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; Trump has said he would seek a quick deal between Ukraine and Russia.

Still, some congressional Republicans have urged Biden to loosen the rules.

The capability would most likely be used first in the Kursk region of Russia, where Ukraine is fighting against North Korean troops as well as Moscow’s forces, sources told Bloomberg on condition of anonymity.

Moscow, with Pyongyang’s help, has been trying to dislodge Ukrainian forces from Kursk after they captured some areas in a surprise incursion earlier this year. Some leaders will most likely raise the issue of North Korean military involvement, including with China, at the G20 leaders summit in Brazil this week.

Pyongyang has also supported Russia with millions of rounds of artillery ammunition and other weapons. The US is expected to adopt more sanctions against North Korea before Biden leaves office, some of the people said.

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