Hello and welcome to News Hour. It's coming to you live from the BBC World Service

studios in Central London. I'm Tim Franks. In the two and a half years since Vladimir Putin ordered the full scale

invasion of Ukraine, they've been the old incursions back over the border

into Russia by small numbers of Ukrainian troops or allied Russian paramilitaries or even drones.

But there's been nothing like this, nothing like the week-long slash into a chunk of

Russian territory. How big a chunk? Well listen to this from the

head of the Ukrainian military Alexander Sierski in an on-camera briefing for

President Selensky. During our offensive on the territory of the Kursk region, as of right now, around 1,000 square kilometers of the Russian Federation are under our

control. Our units are carrying out the assigned tasks. Practically there are battles

on the entire front line. The situation is under our control.

1,000 square kilometers of southern western Russia being occupied by Ukrainian forces

according to the commander-in-chief of those armed forces.

Christopher Miller is Ukraine correspondent for the Financial Times and has just been to the border close to where the Ukrainian troops crossed into Russia.

I was within view of the Russian border where there were dozens of Ukrainian military vehicles, heavy armored

equipment, self-propelled weaponry, various howitzers, troops from various brigades outfitted with high-powered rifles.

It was a really kinetic situation.

There were explosions sounding in the distance, Ukrainian fighter jets

zooming really low over the skies as to not be detected by Russian radar and

and Russian air defenses. It was very clear that this was a much larger scale operation

than we immediately believed in the first couple of days a week ago. And it was also apparent that the Ukrainians were essentially having their way in the first days against their Russian adversaries.

The troops that I spoke with near the border there were explaining that they entered with relative ease and caught their Russian counterparts completely by surprise.

One unit that was operating an American striker fighting vehicle told me they rammed right into a picnic table that was filled with several Russian border guards and soldiers who were sipping coffee.

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