Moscow, Russia - The Kremlin said Monday that US President Joe Biden's outgoing administration will further inflame tensions by allowing Ukraine to use long-range missiles for strikes inside Russia.

Kremlin spokesperson Dmitry Peskov said he had seen media reports that Biden cleared strikes, adding: "It's obvious that the outgoing administration in Washington intends to take steps in order to continue fueling the fire and provoking further escalation of tensions."

A US official, speaking on condition of anonymity, confirmed to AFP reports from The New York Times and The Washington Post that the major policy shift – long demanded by Ukraine – was in response to North Korea deploying troops to help Moscow's war effort.

Ukrainian President Volodymyr Zelensky has long pushed for authorization from Washington to use the powerful Army Tactical Missile System, known by its initials ATACMS, to hit targets inside Russia.

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"If such a decision was really formulated and announced to the Kyiv regime, then of course it's a qualitatively new spiral of tensions and a qualitatively new situation from the point of view of the US' engagement in the conflict," Peskov told journalists.

He said President Vladimir Putin had expressed Russia's position clearly in September when the leader said that such a move would put NATO "at war" with Russia.

In such a case, "we will take the appropriate decisions based on the threats that we will face," Putin said in September.

Peskov said Monday that Putin's position is that such strikes would ultimately be carried out not by Ukraine but by the countries that give permission for such use of missiles.

The Kremlin spokesperson said this was because "the targets are set not by Ukrainian military but by specialists from these Western countries. That fundamentally changes the modality of their engagement."

"That's the danger and provocative nature of this situation," he added.