Jonathan Beale
BBC defence correspondent

A western official says the suspected attack on Saky Airbase in Crimea last week knocked out more than half of Russia's combat naval aviation in the Black Sea fleet.

The unnamed official said such attacks behind Russian lines would boost Ukrainian morale - though it had not impacted the overall "stasis" in the war.

The official said it was still difficult for the West to interpret what had happened with a series of explosions in Crimea. He said the Ukrainians had been tight lipped.

But the official speculated that Ukraine could have used "novel capabilities" along with "incredibly brave people". He said Ukrainian Special Forces had the ability to operate behind enemy lines.

The official said they were watching very closely the situation at the nuclear power plant.

He said concerns were less about direct fire hitting the nuclear reactors as the reactors had been designed to withstand force.

Rather, he said they were concerned about a disruption to the power supply needed to cool the reactors.

At present, the diesel generators needed for that are still working. The official said the plant had a total of six nuclear reactors, of which two are currently operating fully. The plant supplies 20% of Ukraine’s energy needs.

Image source, Reuters

International inspectors could be allowed to visit the Zaporizhzhia power plant next month, a Russian diplomat says.

Calls for neutral experts to be allowed to inspect the plant have intensified in recent weeks, since Russia and Ukraine have each accused the other of shelling the site.

United Nations Secretary General Antonio Guterres, visiting Ukraine at the moment, is among those who have called for inspectors from the International Atomic Energy Agency (IAEA) to be allowed to access the plant, which was seized by Russia in March but has continued to operate, with Ukrainian staff kept on.

Mikhail Ulyanov, Russia's representative to international organisations in Vienna, where the IAEA is based, says: "We are currently discussing this issue with the IAEA Secretariat. Almost every day I speak with the agency's director general, Rafael Grossi."

He says discussions will continue next week over issues such as the number of inspectors, the route they will take, how long they would stay and tasks to be carried out.

"As for the timing of the visit, predictions are not always true, but my feeling is that it could very well take place in early September," Ulyanov says.

Image source, Getty Images

Our Europe editor Paul Kirby has been looking more closely at the risk factors involved with the crisis at Ukraine's Zaporizhzhia nuclear power plant.

• Build of the facility - The plant is robust, so rocket damage doesn't pose a high risk, says Prof Iztok Tiselj, chair of nuclear engineering at the University of Ljubljana in Slovenia. After 9/11, nuclear plants were tested for potential attacks involving large airliners and found to be largely safe
• Spent fuel pools - These provide some cause for concern, but even if there was a release of radioactivity, Prof Tiselj believes it would be so small as to be negligible. Ukraine's nuclear agency has warned that loss of power used for cooling this spent fuel could cause it to melt. It says three of the four power transmission lines linking the plant to Ukraine have already been damaged and diesel generators will not provide a long-term solution if the last source of power is broken.
• Pressure on staff - Ukrainian workers are managing the plant under Russian occupation, which poses a welfare concern. The human factor poses the biggest risk of an accident at Zaporizhzhia, argues Dr Mark Wenman, head of the Centre for Doctoral Training in Nuclear Energy Futures.

Read more from Paul here.

Russia's President Putin and France's President Macron have agreed on the need for a visit to the Zaporizhzhia nuclear power plant by inspectors from the International Atomic Energy Agency (IAEA), the Kremlin says.

During their phone call a short time ago, Putin blamed Kyiv for recent shelling of the facility, it adds..

Ukraine has previously levelled the same accusation at Russia.

Image source, Reuters

What's been happening at the power plant since the war started?

• March 2022: Shortly after invading Ukraine, Russian troops seize the plant, though Ukrainian staff continue with daily operations
• July: Russian forces reportedly deploy rocket launchers in the complex, turning it into a military base
• 3 August: The International Atomic Energy Agency says the plant is "completely out of control", and needs an inspection and repairs
• 5 August: Ukraine's nuclear agency says two rounds of Russian rocket fire prompted its operators to disconnect a reactor from the power grid
• 8 August: Ukraine says Russian shelling has damaged three radiation sensors and injured a worker. Local Russian-backed authorities accuse Ukrainian forces of attacking the site
• 10 August: Foreign ministers from the G7 group of nations say Russia must immediately hand back control of the plant to Ukraine
• 11 August: More shelling of the plant is reported, with Ukraine and Russia again blaming each other, and employees tell the BBC they're kept at gunpoint
• 18 August: Russia dismisses a UN proposal by Guterres to demilitarise the area around the plant, as employees at the facility appeal to the world, warning of a potential nuclear catastrophe
• 19 August: Ukraine's nuclear agency accuses Russia of restricting access of staff to the plant and preparing to disconnect power units supplying the Ukrainian electricity grid

Image source, EPA

If you're just joining us, or would like a refresher, here's a recap of some of the main headlines from Ukraine today.

• Russian forces around the Zaporizhzhia nuclear power plant aim to disconnect energy produced there from the Ukrainian power grid, Ukrainian officials say
• The UN Secretary-General António Guterres - who is in Ukraine - has warned Russia against doing so, saying it's a priority for all military activity around the Zaporizhzhia nuclear complex to end, and for a team of inspectors to be allowed into the complex
• Russia's Deputy Foreign Minister Sergei Ryabkov, quoted by Reuters, says troops occupying the plant are there to prevent a nuclear accident

• Kharkiv, Ukraine's second largest city, has come under heavy shelling in recent days - like it has for several months. A woman died when a university building was attacked this morning, taking the death toll from shelling of the city in recent days to at least 20
• And in Crimea, at least four explosions were reported overnight near Belbek air force base close to the city of Sevastopol. Western Officials say Ukraine’s recent ability to strike deep behind the lines in the occupied region is having both an operational and a psychological effect on Russia’s military

As we've been reporting, Ukraine's nuclear energy company Enerhoatom has said , externalthat Russian troops controlling the Zaporizhzhya nuclear power plant may be planning to cut it off from the lines that feed power into the Ukrainian energy system in the near future.

Enerhoatom has posted on Telegram warning that the Russian military is currently looking for fuel suppliers "for the diesel generators, which are expected to switch on after the power units are shut down". It suggests these generators would be needed to keep power supplied to cooling systems for spent nuclear fuel.

The company went on to claim that the Russians have filmed their own shelling at the site, with the aim of sharing the footage and blaming Ukrainian forces. BBC News has been unable to verify these claims. In recent days both sides have been trading accusations that the other is about to stage a "provocation" at the plant.

"Once again we call on the international community to take all necessary measures as soon as possible to de-occupy the Zaporizhzhya [power plant] because the nuclear and radiation safety of all mankind is at stake," Enerhoatom said.

Image source, Reuters

So should we be worried about any potential nuclear fallout from what is going on in Ukraine?

Mark Wenman, who is reader in nuclear materials at Imperial College London and director of the EPSRC Centre for Doctoral Training in Nuclear Energy Futures, says there does not appear to be any cause for concern currently.

"These reactors are designed much more to Western standards," he tells BBC News.

"Zaporizhzhia was built in the 1980s which is relatively modern. It has a solid containment building - it’s 1.75m (5.7ft) thick of heavily reinforced concrete on a seismic bed. It takes a hell of a lot to breach that.

"People forget [about] the 1979 nuclear accident at Three Mile Island [in the US] which is the same kind of design of pressurised water reactor. In that accident, the operators managed to melt the reactor core and there was no radioactive release on site, so no widespread contamination.

"So if there was an accident at Zaporizhzhia, that is the worst-case scenario that I could envisage.

"After 9/11, we did a lot tests on those buildings - what if someone flew large airliners - and the conclusion was they don’t really do anything to them.”

Read more about the Three Mile Island incident, the worst nuclear disaster in US history here.

Frank Gardner
BBC News, Security Correspondent

Image source, Russian Defence Ministry

Western officials say that Ukraine’s recent ability to strike deep behind the lines in Russian-occupied Crimea is having both an operational and a psychological effect on Russia’s military.

They estimate that the explosions at Russia’s Saki airbase on 9 August, and other attacks, have put more than half of its Black Sea fleet’s naval aviation out of action.

This, combined with the loss of its flagship, the Moskva, sunk by Ukrainian missiles, and Russia’s hurried abandonment of Snake Island, has reduced the once-proud Black Sea fleet to little more than a coastal flotilla that is now having to adopt a cautious, defensive posture.

The officials, who were speaking unattributably on background, doubted the ability of Russia to threaten an assault on the Ukrainian port of Odesa any time soon.

The fact that the explosions in Crimea, in a place previously considered to be well beyond the reach of any Ukrainian attack, were watched by thousands of Russian tourists, many of whom have since fled Crimea back into Russia, has had a psychological effect in Moscow, say officials.

There is still some confusion about whether the commander of Russia’s Black Sea fleet has been replaced or not.

Image source, EPA

UN chief António Guterres has asked that the Russian-occupied Zaporizhzhia nuclear power station not be cut off from Ukraine's grid, after reports that Moscow was planning to do so.

"Obviously, the electricity from Zaporizhzhia is Ukrainian electricity... This principle must be fully respected," he is quoted as saying by the AFP news agency during a visit to the port of Odesa in southern Ukraine.

James Waterhouse
Reporting from Zaporizhzhia

We arrive at a supermarket car park where emergency workers are dressed in yellow hazmat suits. They are practising cleaning drills in the event of a radioactive contamination.

They are watched by senior officials, who are keen to see how ready the region would be in the event of a worst-case scenario.

"Of course we are concerned," Ukraine's Energy Minister Herman Halushchenko tells me. "The situation changed dramatically when the Russians started shelling the area on 5 August."

Ukraine says the situation at the plant is "approaching critical".

Read more from James here.

Hugo Bachega
BBC News

The UN Secretary-General António Guterres has said it's a priority that all military activity around the Zaporizhzhia nuclear complex ends, and that a team of inspectors is allowed into the complex.

In an interview with BBC News in Odesa, Guterres said there was a "long way for serious discussion", after Russia rejected his call for the creation of a demilitarised zone around the plant.

Russia and Ukraine have accused each other for shelling the plant, which has raised fears of a catastrophe.

Guterres described the situation as "very confusing".

Multiple calls for international inspectors to be allowed into the complex, which has been under Russian occupation since March, have failed to result in a deal.

Image source, EPA

The world is on the verge of a nuclear disaster due to the occupation of the Zaporizhzhia nuclear plant, Ukrainian President Volodymyr Zelensky says.

In a tweet, external, he asks: "How long will it take the global community to respond to Russia's irresponsible actions and nuclear blackmailing?"

Zelensky also spoke about the situation at the power station during his nightly address to the Ukrainian people.

He says there are "no objective obstacles" to stop inspectors from the International Atomic Energy Agency visiting the plant - something the IAEA, an autonomous body within the United Nations, has been calling for.

The president says he discussed with UN Secretary General Antonio Guterres yesterday how the mission could get to the plant quickly and safely through Ukrainian territory.

But he said it should not be Russia that organises any inspection, saying: "The one who organised nuclear blackmail certainly cannot be the transporter of any such missions."

Image source, Getty Images

Russia's military presence at the Zaporizhzhia nuclear power plant is a guarantee against a "Chernobyl scenario", Moscow says.

Russia's Deputy Foreign Minister Sergei Ryabkov, quoted by Reuters, says troops occupying the plant are aiming to prevent a repeat of the 1986 disaster - considered the world's worst nuclear accident.

Fears of another nuclear disaster have been voiced as the shelling of the site has continued.

International bodies such as the United Nations have joined calls for Zaporizhzhia to be demilitarised.

And as Ryabkov's comments today show, those calls continue to be rejected by Moscow.

Our colleagues at BBC Newsround have produced a good guide to what happened at Chernobyl and its lasting impact.

Image source, Reuters

Turkish President Tayyip Erdogan has said he will discuss the issue of the Zaporizhzhia nuclear power plant with Russian President Vladimir Putin, after holding talks with Ukrainian President Volodymyr Zelensky.

Zelensky requested that Russia remove all mines near the plant during the meeting, Erdogan told reporters on his flight back from Ukraine where the two leaders met on Thursday.

"We will discuss this issue with Putin and ask him specifically for Russia to do what it must as an important step for world peace," he said.

Erdogan's visit to Ukraine was his first to the country since Russia invaded earlier this year. On Thursday, he met Zelensky and UN Secretary General António Guterres.

"We do not want to experience another Chernobyl," he said after that meeting.

Erdogan - who has kept diplomatic lines open with Moscow - sees himself as a broker between the two sides, correspondents say.

Returning to concerns about the Zaporizhzhia nuclear plant and while Ukrainian officials and the UN secretary general have warned about the threat to it, the Ukrainian staff who are working there are also sounding the alarm.

They say the site has become "the target of continuous military attacks" in the past two weeks.

"What is happening is horrific and beyond common sense and morality," staff wrote in a Telegram post (in Ukrainian)., external

Russian forces seized the site, the biggest nuclear plant in Europe, in early March but kept on its Ukrainian staff as technicians.

Three of the four power supply lines linking the plant to the Ukrainian national grid have now been damaged by shelling and Ukraine's nuclear regulator has warned that a complete loss of power supply would mean that "nuclear fuel will begin melting, resulting in a release of radioactive substances to the environment".

On Thursday, the Ukrainian government said that members of Rosatom, Russia's state nuclear corporation, had "urgently" left the facility, and warned that Russia could be "preparing a provocation".

Despite concerns, though, the site is said to be far more secure than the Chernobyl plant - the site of the worst nuclear incident in history.

The reactor is in a steel-reinforced concrete building that can "withstand extreme external events, both natural and man-made, such as an aircraft crash or explosions," experts told the BBC in March.

As we mentioned earlier, the Crimean peninsula - which was annexed by Russia in 2014 - has come under another series of attacks, the third in 10 days.

At least four explosions were reported overnight near Belbek air force base close to the city of Sevastopol.

The Russian-appointed local head said air defences had shot down a Ukrainian drone, while claiming the blasts had caused no damage.

Last week, the Saky airbase on the peninsula was hit by explosions that destroyed at least nine Russian warplanes.

And this week, an arms depot was targeted, with Russia blaming sabotage for the first time.

On Thursday evening, another Russian-appointed local official said air defences had been activated in the city of Kerch, in the far eastern tip of the peninsula - the gateway to a bridge that links Crimea with Russia.

He claims "there is no danger to the city and the bridge".

Image source, Reuters

As we've been reporting, Kharkiv has come under heavy shelling for months, and regional officials are reporting at last five more Russian missile attacks on the city this morning.

At least one woman, a 52-year-old guard at an educational establishment, was killed, the head of the regional military administration, Oleh Synyehubov, says on Telegram.

That takes the death toll in the city in the past few days to at least 20.

Synyehubov says a university building has been destroyed and residential, business and farm buildings along with a library have been damaged this morning. Wheat and grass in fields are burning, he adds.

He says fighting continues on the front line, with Ukrainians forces shelled from fighter planes, helicopters and tanks.

As we've been reporting, Ukraine's nuclear agency - Energoatom - is sounding the alarm over what it says are Russian plans "in the near future" to disconnect power units at the Zaporizhzhia plant from the Ukrainian power system.

This is something Russia has spoken about before, with its deputy prime minister saying in May that Russia would disconnect the Zaporizhzhia plant from Ukraine's energy grid and instead integrate it with Russia's energy system if Kyiv refused to pay for the plant's electricity.

But at the time, a spokesman for Energoatom told the BBC that it would take years to link the plant with Russia.

"The Russians can build a power line theoretically, but it will take a long time," Leonid Oliynyk said.

"Now the power station is working at a minimum level, but Kyiv remains in charge, all the power lines are controlled by Ukraine. The Russian statement is wishful thinking," he told us.

Before the war, the plant generated 20% of Ukraine's electricity. It continues to be run by Ukrainian workers, but is under Russian control.

Ukraine's second-largest city Kharkiv has been one of the most consistently shelled places since the Russian invasion began in February, and hundreds of people there have died.

About 19 people were killed in Russian shelling on the north-western city on Wednesday afternoon and Thursday morning, according to officials, and another woman has died after at least five more missile attacks this morning.

The UK’s Ministry of Defence believes Kharkiv is being targeted because of its location, sitting about 15km from the Russian front line and within range of most types of Russian artillery.

In its morning intelligence update, external, the MoD says Russian forces are continuing to attack Kharkiv because “they are probably trying to force Ukraine to maintain significant forces on this front to prevent them from being employed as a counter-attack force elsewhere”.

As we have previously reported, Ukraine's armed forces have for weeks been talking of launching a counter-offensive in the south and recapturing the city of Kherson.

You can read more about this here.

Image source, .