Ukraine-Russia war latest: As Ukrainian troops advance into Russia

"They (Ukraine) look as if they've taken over at least a dozen settlements," he says. 

"They've pushed in towards Sudzha, which is a logistical hub, and they've been fanning out, northeast and southeast from there," he adds. 

Sudzha is the last operational trans-shipping point for Russian natural gas to Europe via Ukraine.

"They're miles deep into Russia... and that's big - that's not just a raid," Professor Clarke concludes. 

As for Russia's response, he's not been impressed.

"The Russians thought they could deal with it with a few of their reserve battalions," he says, adding "that's not happening". 

If they want to push the Ukrainians back, "they're going to have to commit more [resource]" to Kursk. 

Russia claims Ukrainian operation on Kinburn Spit was foiled

We're getting more information now on the Ukrainian special forces operation on the Russian-occupied Kinburn Spit in the Black Sea. 

Ukraine says it destroyed six units of Russian armoured vehicles and that "about three dozen invaders were eliminated". 

However Russia's defence ministry, quoted by the Interfax news agency, said the raid was repelled. 

It said some of the Ukrainian forces were stopped by mines and the rest were gunned down with firearms. 

Moscow claimed Ukraine lost 16 "saboteurs" in the operation. 

The Kinburn Spit is in Ukraine's southern Mykolaiv region and juts out into the Black Sea. 

Moscow's military vantage point on the spit is seen as one of the reasons why Ukraine cannot reopen its ports of Mykolaiv and Kherson and export goods from them via its Black Sea shipping corridor.

Zelenskyy briefed on 'defensive actions' in Russia

Volodymyr Zelenskyy has said his army chief has briefed him on the Ukrainian military's "defensive actions" taking place in areas used by Russia to launch airstrikes.

The Ukrainian president did not specifically mention the incursion into Russia's Kursk region which has made headlines this week. 

Ukraine has offered little information on the operation, with few updates coming through on what exactly is happening. 

Russian troops regularly conduct air attacks on Ukraine from the Kursk region. 

Fourteen now dead in supermarket attack

Throughout the day we've been bringing you updates on a suspected Russian attack on the Ukrainian town of Kostiantynivka. 

Ukrainian officials now say at least 14 people have been killed in the attack on a supermarket, up from a previously reported 12 deaths. 

Volodymyr Zelenskyy earlier said there were people under the rubble of the supermarket and a post office. 

Nova Poshta, Ukraine's largest private postal company, said its cargo office in the supermarket was damaged in the strike. 

"All our employees are alive. One colleague received a concussion – he is getting all the necessary help," the company said on X.

Ukrainian special forces carry out raid on occupied Kinburn Spit

Away from Ukraine's incursion into Russia's Kursk region, Ukrainian special forces have also conducted an amphibious raid on the Russian-occupied Kinburn Spit. 

The operation destroyed six Russian armoured vehicles and personnel, the Ukrainain military intelligence agency said.

The Kinburn Spit is in the southern Mykolaiv region and juts out into the Black Sea. 

It was captured by Russia at the start of its full-scale invasion in 2022.

If you're just joining us, here is a reminder of what we know so far about Ukraine's incursion. 

Fighting has continued in the Kursk region of Russia for a fourth day after Ukrainian forces smashed through the border earlier this week.

There is much that remains unclear and Ukraine remains tight-lipped about what is happening - and what its broader goal for the operation is.

These are the main things we know...

As many as 6,000 Ukrainian troops may have crossed the border, reports suggest

Fighting around the town of Sudzha has been ongoing and some military bloggers have suggested that it is now under Ukrainian control

The ISW thinktank has estimated that Ukrainian forces may have penetrated up to 35km (20 miles) inside Russian territory

Russia has claimed to be repelling Ukrainian efforts, but it is not clear whether this is true

Ukraine has yet to comment on the Kursk incursion, and operational security in general for Kyiv's forces has been very tight

The US has said it does not consider the action in Kursk to be escalatory.

Mathieu Boulegue, a defence analyst at the Chatham House thinktank, has said the Ukrainians appear to have a clear goal in mind, even if they're not saying what it is.

“Such a coordinated ground force movement responds to a clear military objective, yet unknown, that requires extreme operational security,” he said.

At the same time, the raid spooks the Russian public and delivers a slap in the face to Russian President Vladimir Putin, offering Ukraine "a great PR coup," he added.

The attack "is a massive symbol, a massive display of force [showing] that the war is not frozen, the war is coming to you".

Number killed in supermarket strike rises to 12

The number of people who died in a Russian strike on a supermarket in the Donetsk region has risen to 12, Ukraine says.

At least four homes, a shopping centre, a post office, shops and a car wash were damaged in the attack on Kostiantynivka.

Images from the scene showed thick black smoke pouring into the air as firefighters picked through the rubble.

Some 44 people were injured in the strike, which reportedly involved a Kh-38 missile.

While the full extent of Ukraine's incursion into Russia remains unclear, the town of Sudzha has been a focus over the last few days.

Located around 10.5km (6.5 miles) from the border with Ukraine, it is around 100km from the regional capital, the city of Kursk.

Sudzha had been home to around 5,000 people and is the site of an important gas transportation hub.

But after Ukrainian forces broke across the border on Tuesday in a shock counter-offensive, it is no longer certain that Sudzha is under Russian control.

Ukrainian troops that have crossed the border - and it's thought there could be several thousand - have been reportedly expanding the areas under their control. 

Burnt-out Russian convoy pictured in Kursk

A Russian convoy of armoured vehicles has been destroyed by an apparent Ukrainian attack along a road in Kursk.

This image, verified by the Reuters news agency, shows the aftermath of the strike. 

The convoy was apparently hit near the Oktyabrskoye village, and according to the monitoring group DeepState, approximately 13 trucks carrying personnel were destroyed in the strike.

It appears there have been numerous fatalities based off social media videos, although this is unconfirmed. 

Neither Russia nor Ukraine has commented on the claims. 

At least two people have died following that Russian attack on a supermarket we reported in our previous post, according to the regional governor. 

Vadym Filashkin added that 17 were wounded and that a search and rescue operation was under way in Kostiantynivka.

He said earlier that the supermarket was hit by Russian barrell artillery. 

He also shared this image... 

Russia has struck a supermarket in the city of Kostiantynivka, injuring seven people, according to reports. 

The city lies in the Donetsk Oblast. 

"The Russians shelled the city with barrel artillery, hitting a supermarket," the local governor said, adding that one of the injured is in a serious condition. 

"The attack on the supermarket in Kostyantynivka is another terror of the Russians," head of President Volodymyr Zelenskyy's office Andriy Yermak said.

This image comes to us from the scene. 

-SKY NEWS