The Russian president Vladimir Putin on Monday travelled 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.

Mr Putin’s trip to the Sevmash shipyard in Severodvinsk, in Russia’s north-western Archangelsk region, comes three days after he declared his intention to seek another six-year term.

Mr 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 Mr Putin oversaw raising the navy’s flag on the newly built Emperor Alexander III and the Krasnoyarsk nuclear submarines, also appeared to emphasise his focus on bolstering Russia’s nuclear forces amid the tensions with the US and other Nato allies over Ukraine.

Mr 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, Mr Putin pledged to carry out plans to modernise the Russian navy.

The Emperor Alexander III is the seventh Borei-class nuclear-powered submarine to enter service.

Each of them is armed with 16 nuclear-equipped Bulava intercontinental ballistic missiles.

Mr 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 is armed with cruise missiles and torpedoes, and is designed to hunt for enemy submarines and is also capable of attacking ground targets.

Mr Putin said that another five Yasen-class submarines are being built.