Russian President Vladimir Putin on Monday traveled to a shipyard to attend the commissioning of new nuclear submarines, a visit that showcased the country's nuclear might amid the fighting in Ukraine.

Putin's trip to the Sevmash shipyard in Severodvinsk in Russia's northwestern Archangelsk region comes three days after he declared his intention to seek another six-year term.

Putin announced his decision to run in the March 17 presidential election, which he is all but certain to win, while speaking to soldiers who fought in Ukraine after a Kremlin award ceremony — a setting that underlined his focus on the military action in Ukraine.

Monday's visit to Sevmash, where Putin oversaw raising the navy's flag on the newly built Emperor Alexander III and the Krasnoyarsk nuclear submarines, also appeared to emphasize his focus on bolstering Russia's nuclear forces amid the tensions with the U.S. and other NATO allies over Ukraine.

Putin has cast his decision to send troops into Ukraine in February 2022 as a response to what he described as Western efforts to threaten Russia and undermine its security, while Ukraine and its allies have denounced the action as an unprovoked act of aggression.

Speaking at the shipyard, Putin pledged to carry out plans to modernize the Russian navy.

The Emperor Alexander III is the seventh Borei-class atomic-powered submarine to enter service. Each of them is armed with 16 nuclear-tipped Bulava intercontinental ballistic missiles.

Putin announced that three more such submarines are under construction. They are part of Russia’s nuclear triad, which also includes land-based nuclear missiles and nuclear-armed strategic bombers.

The Krasnoyarsk is a nuclear-powered submarine of the new Yasen type. It's armed with cruise missiles and torpedoes, and is designed to hunt for enemy submarines and is also capable of attacking ground targets. Putin said that another five Yasen-class submarines are being built.

At Sevmash, Putin also visited the Admiral Kasatonov frigate of Russia's Northern Fleet, one of the most advanced ships of the Russian navy that is armed with new Zircon hypersonic cruise missiles.

Putin commissions two nuclear submarines and says more are to come.

Russian President Vladimir Putin travelled to the northern city of Severodvinsk on Monday to attend a televised flag-raising ceremony for two nuclear submarines, the Krasnoyarsk and Emperor Alexander the Third.

During his visit to the Sevmash shipbuilding yard, Putin said both nuclear-powered vessels would soon take up duty in the Pacific.

He emphasised that they were part of two separate series of submarines that Russia is rolling out.

"We will quantitatively strengthen the combat readiness of the Russian Navy, our naval power in the Arctic, the Far East, the Black Sea, the Baltic Sea, and the Caspian Sea - the most important strategic areas of the world's oceans," he said.

Putin, who last Friday announced he would seek another presidential term in an election due in March, has repeatedly talked up the potential of Russia's new generation of weapons, particularly its nuclear systems, and their value as a deterrent to the West.