The order comes in a meeting with the country's security council, which was partially televised.
Furthermore, Putin continued, Russia views all attacks with conventional weapons carried out by a non-nuclear state with the help of a nation with nuclear capability as a joint attack where both countries are considered the attacking party.
He did not specify, however, whether Russia would respond with nuclear weapons to such an attack.
The statement implies a change in Russia's nuclear doctrine. The conditions for Russia's transition to using nuclear weapons have been clarified, according to Putin.
We see that the modern military and political situation is dynamic and changing, and we must take that into account. It includes new forms of military threats and risks to Russia and our allies, he said.
He also warned that Russia considers itself entitled to use nuclear weapons if Belarus is attacked, even if it is with conventional weapons.
Vladimir Putin has previously warned the USA and NATO that giving Ukraine the green light to strike with advanced weapons at targets deeper in Russia would mean war with NATO.
He has also said that the doctrine is a living document that can be changed as needed, and that Moscow assumes that there will never be an exchange of nuclear attacks, according to Tass.
