Russia just threatened NATO with nuclear weapons over Kaliningrad

Russia just told NATO something big.

If NATO tries to cut off Kaliningrad, Russia will use nuclear weapons.

That warning is sitting in a real document. Sent to NATO countries a few hours ago. Seen by Reuters.

Russia calls it a non-paper. That's diplomatic speak for an informal message. Not a treaty. But it's still one government talking straight to another.

So where is Kaliningrad, and why does this matter?

It's a Russian exclave on the Baltic Sea. Squeezed between two NATO countries, Poland and Lithuania. About the size of Connecticut. And it holds Russia's Baltic fleet, plus nuclear-ready Iskander missiles.

Here's Russia's claim. It says it has information suggesting NATO is preparing an air and naval blockade of the region.

NATO has not confirmed any such plan.

The document accuses NATO of a dangerous and reckless course. One that carries, it says, high risks of direct armed conflict. It even raises the idea of Russian strikes on NATO countries' decision-making centres, right from the start of any conflict.

Then the warning itself. Russia says quote "Russia will be ready to use the entire arsenal of forces and capabilities at its disposal, including nuclear weapons" to defend its territory if NATO tries to isolate Kaliningrad from the rest of the country.

So Russia has put nuclear weapons on the table. Over a blockade NATO says it isn't even planning.

A senior European defence official told Reuters this is the first time since the Cold War that Russia has threatened NATO this directly. The official called it serious.

NATO wrote back. And it rejected the claim completely.

NATO says none of its exercises or activities threaten Russian territory. It's telling Russia to end what it calls its unprovoked full-scale invasion of Ukraine. And to stop what it calls irresponsible nuclear rhetoric.

A NATO diplomat told Reuters the Russian letter is just another attempt to intimidate Europeans. The diplomat says NATO's response is firm and responsible, and that NATO will not be dissuaded from supporting Ukraine.

Mark Rutte, NATO's Secretary-General, said even more in public.

He said NATO is a defensive alliance. He told Russia to stop the nuclear threats. He called the document unhelpful.

Someone asked him directly: is the risk of nuclear weapons being used against the Baltic states real?

He says quote "Putin knows that he can never win against NATO, so I don't take this that seriously".