Russia reserves the right to retaliate for nuclear attacks, according to a decree on the fundamentals of Russia’s state policy of nuclear deterrence, which was signed by President Vladimir Putin.

“The Russian Federation reserves the right to launch a nuclear strike either in response to a similar attack or in the event of a threat to the existence of the state,” the decree reads on Tuesday.

Russia’s policy is defensive in nature and is aimed at maintaining its capabilities at a level sufficient to ensure nuclear deterrence, guarantee the protection of its sovereignty and territorial integrity, and prevent aggression against the country or its allies.

Putin on Monday held a telephonic conversation with his US counterpart Donald Trump at the initiative of the US side and discussed issues related to the Group of Seven (G7) Summit and oil markets.

The importance of enhancing the bilateral dialogue on strategic stability and confidence-building measures in the military sector was noted.

Russia considers the creation and deployment of missile defence systems and strike systems in space as a threat, and its neutralization requires nuclear deterrence, the decree said.

Russia was expelled from what was then the G8 in 2014 when Trump’s predecessor, Barack Obama, was US president, after Moscow annexed the Crimea region from Ukraine.

Russia still holds the territory, and various G7 governments have rebuffed previous calls from Trump to re-admit Moscow.