President Vladimir Putin has updated Russia’s nuclear doctrine, two days after his US counterpart Joe Biden granted Ukraine permission to strike targets deep inside Russia with US-made weapons.

Under the updated doctrine issued Tuesday, Moscow will consider aggression from any non-nuclear state – but with the participation of a nuclear country – a joint attack on Moscow.

The Kremlin began this fresh round of nuclear saber-rattling Tuesday, saying the revised military doctrine would in theory lower the bar to first use of nuclear weapons.

In a phone call with reporters Tuesday, Kremlin spokesperson Dmitry Peskov noted the changes mean that “the Russian Federation reserves the right to use nuclear weapons in the event of aggression using conventional weapons against it and/or the Republic of Belarus.”

Nuclear deterrence is a pillar of Russian military doctrine, but the revision appears to broaden the definition of what would be considered aggression against Russia.

“An important element of this document is that nuclear deterrence is aimed at ensuring that a potential adversary understands the inevitability of retaliation in the event of aggression against the Russian Federation or its allies,” Peskov said.

The change comes as the Kremlin responds to the Biden administration’s decision to allow Ukraine to use powerful long-range American weapons inside Russia, a move the Russian government has already signaled would be a dangerous escalation of the war in Ukraine.

This is a breaking story. More to come.