The Kremlin has threatened a ‘nuclear response’ should Ukraine strike targets inside Russia with Western-supplied long-range missiles.

‘The Russian Federation reserves the right to use nuclear weapons in the event of aggression with the use of conventional weapons against it,’ Kremlin press secretary Dmitry Peskov told reporters in Russia this morning according to the TASS news service.

His statement came as Putin approved an updated nuclear doctrine that would allow his strategic missile forces to deploy nuclear weapons in the event that Russian territory is threatened by a non-nuclear nation supported by a nuclear power.

Threats that would make Russia’s leadership consider a nuclear strike include an attack with conventional missiles, drones or other aircraft.

A Ukrainian strike on Russian territory with US-supplied missiles would meet these criteria.

Meanwhile, NATO is holding its largest-ever artillery exercise just 70 miles from the Russian border, where the British Army is testing what military chiefs have described as a ‘game-changing’ weapon.

Finland, which joined the military alliance last year, is hosting up to 3,600 soldiers from 28 nations for the exercise, known as Dynamic Front.

Live fire drills began on Sunday in the northern Lapland region, and are part of a series of exercises, with further ones planned in Estonia, Germany, Romania and Poland.

The British Army is using the opportunity to put its Archer 155-mm guns to the test, weapons which can release high explosive shells or GPS-guided munitions and hit targets 30 miles away.

The guns have been labelled a battlefield game-changer by British troops, with Major Barney Ingram telling the i newspaper that ‘you can, realistically, with this capability, neutralise most targets’.

Putin’s tightly-controlled state TV has made open threats of a nuclear attack on Britain and the US in the wake of the Biden administration’s decision to permit Ukraine to use long-distance missiles to target Russian territory.

The Kremlin chief’s propagandists expressed fury at Biden for giving Ukraine the green light to strike targets inside Russia with the coveted ATACMS system that has a range of up to 190 miles.

Moscow also sees it as highly likely that Britain and France will mirror the decision by granting Ukraine permission to use their Storm Shadow and SCALP missiles, though this is yet to be confirmed.

The Russians claim that a strike with Western weapons on Russian soil crosses a line laid down by Putin and directly implicates the West in the war, arguing that Ukraine cannot target these sophisticated missiles to strike Russia without US, British or French assistance.

Andrey Gurulev, reservist Russian army general, hardline MP, and pro-Putin TV propagandist, warned of a full-scale nuclear strike on Britain to show the dictator’s intent.

‘There are individual targets that can be hit with….demonstrative warning strikes,’ he said. ‘The first candidate to get a nuclear bludgeon….is the UK.’

Embarking on a rant on live television, Gurulev said the West was scared of Putin’s hypersonic nuclear arsenal.

‘I assure you that there will be no backlash [against Russia],’ he said.

‘Our arsenal in Russia, 100% deters either Biden or Trump from using nuclear weapons against Russia.’

He also declared that ‘if anyone has the urge to launch ATACMS, SCALP, Storm Shadow missiles… there will be essentially nothing left of America trying to pull us into escalation.

‘There will be no Biden and no Trump. The American people and we know this perfectly well.’

Meanwhile, in a UN security council debate marking the 1,000th day of war in Ukraine, Putin’s permanent representative to the UN Vasily Nebenzya said the use of Western missiles in Russia amounted to ‘suicidal strikes’.

He also urged a rethink from Britain and France.

‘Regardless of the militaristic fervour of the Democratic administration, which, having lost the presidential election with a bang… is giving suicidal permits to Zelensky’s regime to use long-range weapons to strike deep into Russian territory.

‘Perhaps Joe Biden himself, for many reasons, has nothing to lose,’ he said.

‘But the short-sightedness of the British and French leadership, which are rushing to play along with the outgoing administration and dragging not only their countries but the whole of Europe into a full-scale escalation with extremely serious consequences, is striking.

‘This is exactly what our former Western partners should think about before it is too late.’

Meanwhile, Ukraine marked the 1,000th day of the war by launching a devastating strike on a giant Russian ammunition store, prompting claims Zelensky’s forces used long-range missiles rather than drones to wreak havoc.

The fireball explosion in Karachev, in Russia’s Bryansk region, comes just days after the US gave Kyiv the green light to use ATACMS rockets.

The fiery blast in Karachev, which lit up the night sky and was filmed from several miles away, erupted around 77 miles from the nearest Ukrainian border early this morning.

Munitions supplied by North Korea are believed to have been the target.

Several Telegram reports said the giant mushroom fireball was from a missile strike, though this has not been confirmed.

The same ammunition store was hit in a drone strike last month, but the latest attack caused significantly more damage.

While Ukraine does have domestically made missiles, its usual strikes on Russian territory until now have been by drones rather than Western-supplied missiles.

Russian officials said a dozen drones had also been downed over Bryansk overnight.

Telegram channel Exilenova said: ‘The 67th arsenal of the [Russian armed forces] was attacked in Karachev at night.

‘This time it was a missile.’

A Russian channel with links to law enforcement – VChK-OGPU – reported: ‘A missile alert was declared in the Bryansk region, after which a very powerful explosion occurred in Karachev, according to eyewitnesses.

‘Now residents see a fiery glow and hear less powerful explosions. A large weapons arsenal is located in this place.’

The US has given the go-ahead for long-distance ATACMS strikes on Russian territory, with the guidance that this will be mainly in the Kursk region.

Neither Britain nor France has confirmed – for ‘operational reasons’ – strong suspicions that Ukraine has been given the green light to use Storm Shadow and SCALP missiles against targets inside Russia.

Telegram channel Pravda Gerashchenko – close to the Ukrainian authorities – indicated the Karachev strike was a missile.

There was no initial official comment in Kyiv or Moscow, and no hard evidence either way.

Meanwhile, a Russian strike on Ukraine’s Sumy region killed at least six and left a dozen wounded, including two children.

Two Russian-launched Iranian Shahed kamikaze drones hit a building in Hlukhiv in Sumy region.

Victims were buried under the rubble.

Reports said that a ‘dormitory’ had been hit.