President Putin has said tonight that the US and European countries will be directly participating in Moscow's conflict with Ukraine if they lift restrictions on Kyiv using long-range missiles to strike Russian territory. He said this would change the nature of the conflict and mean the US and other NATO countries were fighting with Russia. Sakeer Starmer, who's currently heading to Washington, is expected to discuss the use of such missiles tomorrow with President Biden. The Prime Minister responded to President Putin by saying it was Russia who started the conflict with its illegal invasion and that it could end it straight away. In a moment, we'll speak to our Russia editor, Steve Rosenberg. But first is Damian Gramaticus.

Two and a half years after Vladimir Putin launched his invasion of Ukraine, and almost nightly, Russian bombs and missiles continue to batter the country. Strikes launch from deep inside Russia. To counter these, Ukraine has for months been urging the West to allow it to use the long-range weapons they already supply to hit back against airfields, logistics, and military targets that sustain these assaults, and to blunt the advances Russia is making on the ground. For Ukraine, the timing with winter coming is critical. So on the agenda for secure Stammer heading to Washington with the foreign secretary, whether to green light attacks on Russian territory. The Russian President warned against that.

If this decision is made, it will mean nothing other than direct participation of NATO countries, the United States, European countries, in the war in Ukraine. It is their direct participation, and this, of course, significantly changes the very essence of the conflict. This will mean that NATO countries, the United States, European countries, are fighting with Russia.

But momentum is building for Western nations to agree to Ukraine's request. Earlier this week, David Lamme and the US Secretary of State traveled to Kyiv. Russia has already been using missiles supplied by North Korea. Now, it's believed to be receiving them from Iran, too.

This week, we have been reminded of how other authoritarian regimes are aiding Putin, with Iran going even further in support for Moscow by providing ballistic missiles, a significant and dangerous escalation.

These are the Stormshadow missiles the UK already supplies Ukraine. Russia warned against doing that. And Ukraine has crossed other Russian red lines, too. Drone strikes of its own deep inside Russian territory, and its recent attack across the border into the Kyrsk region. On his flight, Sakeer Stama said it was Russia that started this conflict, and Ukraine had the right to self-defense. But he wants discussions with a key ally when decisions of such import are made. Damian Cromaticus, BBC News, Westminster.

Well, we'll speak to Damian in Westminster in just a moment. But first to our Russia editor Steve Rosenberg. Steve, these sound like President Putin's most haukish comments to date.

I think so, yes. What we heard from Vladimir Putin today was a clear warning to the West, Do not Do not allow Ukraine to use your missiles to strike Russian territory. What we didn't hear from Vladimir Putin was what Russia is going to do if this actually happens. He talked about taking appropriate decisions, but without any detail. Now, what might those decisions be? Well, in the past, President Putin has proposed providing advanced long-range weapons to Western adversaries to strike Western targets abroad. He's also suggested in the past, deploying find conventional missiles within striking distance of America and its European allies. Now, Russian officials many times have accused the West of fighting Russia, of waging war against Russia on the territory of Ukraine. Putin made it clear today that if this goes ahead, if Western missiles are used to target Russian territory, this will take things to a whole new level. In a sense, Western leaders will have to decide which is greater, the risk of escalation or the need to help Ukraine and allow Ukraine to strike Russian territory with these missiles.

Damian, the Prime Minister on his way to Washington right now, appears to be striking a defiant tone.

Yes. He was very clear in the comments he made on that flight on the way there when he said, Ukraine has the right to defend itself. It was Russia that launched this war. This invasion was launched by President Putin. The point Ukraine makes is that it's fighting at the minute with a hand tied behind its back because Russia is able to strike from deep inside its own territory, those missile attacks into Ukraine, and Ukraine says it cannot respond, and so it wants to. Now, what Sakeer Starmer said on that plane, too, was he said, We do not seek any conflict with Russia. That is not our intention in the slightest. But he did also say that there are important decisions coming up, important moments for Ukraine coming up. It was, he thought, significant that he should spend time sitting down with key allies in Washington because he said, You don't get that time at a normal summit. He wants to have that face-to-face time, he said, to take the strategic and tactical decisions and make sure everyone is on the same page.