Russia has launched extensive exercises of its nuclear forces, including test-firing missiles in a simulation of a retaliatory strike.

President Putin attributed the decision to begin the exercises to “the emergence of new external threats and risks,” adding that “it is important to have modern and constantly ready strategic forces.”

The exercises included the test firing of a Yars intercontinental ballistic missile (ICBM) from the Plesetsk launch pad on the Kamchatka Peninsula and other ICBMs from the Novomoskovsk and Knyaz Oleg nuclear submarines.

The army also conducted training firings of long-range cruise missiles from nuclear-capable Tu-95 strategic bombers.

Putin noted that Moscow would continue to modernize its nuclear forces, deploying new missiles with greater precision, faster launch times and increased capabilities to defeat missile defenses.

The exercises come at a time of escalating tensions with the West, following weeks of signals from Russia that Moscow would respond if the West allowed Ukraine to use longer-range weapons supplied by West to strike deep inside Russia.

Last month, Putin warned that such a move would put NATO at war with Russia.

He also announced a new version of nuclear doctrine, which considers a conventional attack against Russia by a non-nuclear nation backed by a nuclear power to be a joint attack against its country.

Putin also said the revised document envisaged the possible use of nuclear weapons in the event of a massive air attack, leaving the door open for a potential nuclear response to any air attack – an ambiguity intended to deter the West.

During his visit to Beijing, the Finnish president called on China to contribute to the de-escalation of Russian nuclear activity.

“The last and fifth point I made is that it is very difficult to trust President Putin, especially when it comes to nuclear weapons, and that is why it is extremely important that a large power like China continues to engage with Russia and ensures that we can de-escalate the situation as much as possible,” President Alexander Stubb said at a press conference following his meeting with Chinese President Xi Jinping.

Tuesday’s maneuvers follow a series of other exercises by Russian nuclear forces.

Earlier this year, the Russian military held a joint nuclear exercise with Moscow’s ally Belarus, which hosted some of Russia’s tactical nuclear weapons.