Russia has said that Ukraine’s use of long-range ATACMS missiles against its territory marked a “new phase of the Western war” against Moscow, and has said it will react “accordingly”.

Ukraine used the US-made missiles to target a military facility in Russia’s Bryansk border region overnight, Moscow said on Tuesday, just days after Washington gave the green light for Kyiv to use the long-range weapons against Russian targets.

The reported use of the Army Tactical Missile System, known as ATACMS, came as Russian President Vladimir Putin formally lowered the threshold for using nuclear weapons, opening the door to a potential nuclear response by Moscow to even a conventional attack by any nation supported by a nuclear power.

Russia’s Ministry of Defence said Ukraine had struck Russia’s Bryansk region with six missiles, and that air defence systems intercepted five and damaged one.

“This is, of course, a signal that they want to escalate,” Russian Foreign Minister Sergey Lavrov, speaking at a Group of 20 (G20) news conference in Brazil, said of the attack.

“We will be taking this as a qualitatively new phase of the Western war against Russia. And we will react accordingly,” he added, accusing Washington of helping Kyiv operate the missiles.

Russia has long asserted that the ATACMS is programmed by United States specialists and requires guidance from US satellites.

Also on Tuesday, Ukraine’s President Volodymyr Zelenskyy said his country was working with all partners to win their support for longer-range strikes.

When asked about the attack in the Russian Bryansk region, Zelenskyy said Kyiv now had US-ATACMS systems as well as its own long-range capabilities, and would use all of them.

Ukraine’s military did not publicly specify what weapons it had used, but a Ukrainian official source and a US official, both speaking anonymously, told the Reuters news agency that it has used the ATACMS.

New nuclear doctrine  

Lavrov also urged the West to read a decree signed by Putin that lowers the threshold for when Moscow can use nuclear weapons.

“I hope that they will read this doctrine … in its entirety,” Lavrov said.

Russia had been warning the West for months that if Washington allowed Ukraine to fire US, British and French missiles deep into Russia, Moscow would consider those NATO members to be directly involved in the war in Ukraine.

Washington permitted Ukraine to use the longer-range weapons on targets inside Russia after declaring that thousands of North Korean soldiers were deployed in the Russian region of Kursk to fight an incursion by Kyiv’s forces.

The updated Russian nuclear doctrine, establishing a framework for conditions under which Putin could order a strike from the world’s biggest nuclear arsenal, was approved by him on Tuesday, according to a published decree.

While the doctrine envisions a possible nuclear response by Russia to such a conventional strike, it is formulated broadly to avoid a firm commitment to use nuclear weapons and keep Putin’s options open.

The approval of the document demonstrates Putin’s readiness to tap his nuclear arsenal to force the West to back down as Moscow presses a slow-moving offensive in Ukraine as the war reaches its 1,000th day.

Asked on Tuesday if a Ukrainian attack with longer-range US missiles could potentially trigger a nuclear response, Kremlin spokesman Dmitry Peskov answered affirmatively, saying the doctrine provides scope for such a response to a conventional strike that threatens the “sovereignty and territorial integrity” of Russia and its ally, Belarus.

The previous doctrine, contained in a 2020 decree, said Russia may use nuclear weapons in case of a nuclear attack by an enemy or a conventional attack that threatened the existence of the state.

The White House said on Tuesday that the US was not surprised by Russia lowering its threshold for a nuclear strike and does not plan to adjust its own nuclear posture in response.

“As we said earlier this month, we were not surprised by Russia’s announcement that it would update its nuclear doctrine; Russia had been signalling its intent to update its doctrine for several weeks,” the White House National Security Council said in a statement.

Meanwhile, the European Union’s top diplomat Josep Borrell accused Russia of issuing “completely irresponsible” nuclear threats.

“It is not the first time that Putin plays the nuclear gamble,” the outgoing EU foreign policy chief told reporters following defence ministers’ talks in Brussels on Tuesday, saying “any call for nuclear warfare is an irresponsibility”.

British Prime Minister Keir Starmer also denounced the revised nuclear doctrine as the “latest example of irresponsibility” from “the depraved Russian government”, according to spokesperson Camilla Marshall.

“Russia’s the one that continues to escalate this war, and the use of North Korean troops is just one example of that,” Marshall said. “[Putin] could remove his troops, roll back his tanks and end the onslaught and needless bloodshed in both Ukraine and Russia.”