Russian President Vladimir Putin approved a revised nuclear doctrine on Tuesday, indicating that Russia might contemplate the use of nuclear weapons if it faces a conventional missile attack supported by a nuclear-armed nation.

This alteration in Russia’s nuclear policy is a response from the Kremlin to the reported decision by U.S. President Joe Biden’s administration to permit Ukraine to launch American long-range missiles into Russian territory.

The updated doctrine specifies the types of threats that could prompt Russia’s leadership to consider a nuclear response, stating that attacks involving conventional missiles, drones, or other aircraft could fall under these criteria.

Additionally, the doctrine asserts that any act of aggression against Russia by a member of a coalition would be interpreted by Moscow as aggression from the entire coalition.

In the lead-up to the November U.S. presidential elections, Putin mandated these changes to clarify that any conventional assault on Russia, supported by a nuclear power, could be viewed as a collective attack on the nation.

The ongoing war in Ukraine, now in its second and a half year, has resulted in the most serious conflict between Russia and the West since the 1962 Cuban Missile Crisis, which is regarded as the moment when the two superpowers of the Cold War were closest to engaging in deliberate nuclear warfare.