Hello and welcome to NewsHour from the BBC World Service with me, Sean Lay, coming to live from London.

Today, Tuesday, the 19th November, is the 1,000th day since the full-scale Russian invasion of Ukraine began.

Well, mark this milestone by speaking to the most senior Republican on the Armed Services Committee in the US Senate.

We'll hear from Ukrainians who stayed throughout the war and will visit a school in Poland,

educating Ukrainian children seeking refuge there.

But first, to Russia's announcement Tuesday, that Ukraine had for the first time used American-made

attack-ams missiles on Russian territory. The strikes on targets in the Briansk region of Russia

prompted President Putin's foreign minister Sergei Lavrov to accuse the United States of direct

involvement. Physically, attackams are being used, including this early morning in Russia.

And we proceed from the understanding that this is happening

and that any modification of attackams cannot be used without American experts and instructors,

including satellite data, including programming and

targeting. If long-range missiles are going to be applied from Ukraine into Russian territory,

it will also mean that they are operated by American military experts.

That was Sergei Lavrov. Well, his boss, President Putin, today signed a decree altering Russia's nuclear doctrine.

So what's the significance of that? Our Russia editor, Steve Rosenberg, explains.

When we talk about the doctrine, Russia's nuclear doctrine, this is the document that basically sets out the circumstances in which Moscow would consider using nuclear weapons.

But these changes are no surprise.

Weeks ago, President Putin said they were in the pipeline.

Now they've been officially signed and published. The timing of that

clearly linked to the Biden administration allowing Ukraine to strike Russia with longer range

missiles. So what are the key changes? Well, from now on, Russia reserves the right to use

...