Kremlin: Allowing long-range Ukrainian strikes would involve the US

The Kremlin on Monday said Biden's decision to allow Ukraine to strike deep into Russian territory would involve the United States in the war. 

It added these reports have not come from official sources, but if such a decision has been made, it it would usher in a new round of tensions. 

"It is obvious the outgoing administration in the United States wants to throw oil on the fire and escalate the conflict in Ukraine," Russia added.

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

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

The change comes 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.

Ukraine's first deep strikes are likely to be carried out using ATACMS rockets, which have a range of up to 190 miles (306 km), according to the sources.

Since Trump's November 5 victory, senior Biden administration officials have repeatedly said they would use the remaining time to ensure Ukraine can fight effectively next year or negotiate peace with Russia from a "position of strength".

The US' reported decision has raised concerns surrounding the widening of the conflict to involve third parties from the West, rising World War Three. 

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