The Kremlin strongman spoke out after a day of frayed nerves, with Russia test-firing a new generation intermediate-range missile at Ukraine -- which Putin hinted was capable of unleashing a nuclear payload. Ukraine's President Volodymyr Zelensky branded the strike a major ramping up of the "scale and brutality" of the war by a "crazy neighbour", while Kyiv's main backer the United States said that Russia was to blame for escalating the conflict "at every turn".

Intermediate-range missiles typically have a reach of up to 5,500 kilometres (3,400 miles) -- enough to make good on Putin's threat of striking the West.

In a defiant address to the nation, Russia's president railed at Ukraine's allies granting permission for Kyiv to use Western-supplied weapons to strike targets on Russian territory, warning of retaliation. In recent days Ukraine has fired US and UK-supplied missiles at Russian territory for the first time, escalating already sky-high tensions in the brutal nearly three-year-long conflict.

"We consider ourselves entitled to use our weapons against the military facilities of those countries that allow their weapons to be used against our facilities," Putin said. He said the US-sent Army Tactical Missile System (ATACMS) and British Storm Shadow payloads were shot down by Moscow's air defences, adding: "The goals that the enemy obviously set were not achieved".

Kremlin spokesman Dmitri Peskov did however say Moscow informed Washington of the missile's launch half an hour before it was fired through an automatic nuclear de-escalation hotline, in remarks cited in state media. He earlier said Russia was doing everything to avoid an atomic conflict, having updated its nuclear doctrine this week. White House spokeswoman Karine Jean-Pierre told reporters that Washington saw no need to modify the United States' own nuclear posture in response.

Criticising the global response to the strike -- "final proof that Russia definitely does not want peace" -- Zelensky warned that other countries could become targets for Putin too. "It is necessary to urge Russia to a true peace, which is possible only through force," the Ukrainian leader said in his evening address. "Otherwise, there will be relentless Russian strikes, threats and destabilisation, and not only against Ukraine."

The spokesman for UN Secretary-General Antonio Guterres, Stephane Dujarric, said the new missile's deployment was "another concerning and worrying development," warning the war was "going in the wrong direction". Yet a US official played down the threat, saying on condition of anonymity that Russia "likely possesses only a handful of these" experimental missiles.

Russia's envoy to London on Thursday said that meant Britain was "now directly involved" in the Ukraine war, with Andrei Kelin telling Sky News "this firing cannot happen" without UK and NATO support. But the White House's Jean-Pierre countered that it was Russia who was behind the rising tensions, pointing to the reported deployment of thousands of North Korean troops to help Moscow fight off a Ukrainian offensive in Russia's border Kursk region.