This is CNBC's live blog tracking developments on the war in Ukraine. See below for the latest updates. 

Search and rescue operations continue in Chasiv Yar in Donetsk following a catastrophic Russian missile strike on a residential building in the city.

At least 24 people have reportedly died in the attack. "Everyone who gives orders for such strikes ... kills absolutely deliberately," Ukraine's President Volodymyr Zelenskyy said.

Zelenskyy also rebutted claims that Russia has been taking an "operational pause" in the last week, saying that from Ukraine's perspective, hostilities have continued as before and its forces are "repelling assaults in various directions."

U.S. Defense Secretary Austin speaks with Ukrainian counterpart on additional security assistance

U.S. Secretary of Defense Lloyd Austin spoke with his Ukrainian counterpart to provide an update on security assistance, according to a Pentagon readout of the call.

Ukrainian Minister of Defense Oleksii Reznikov shared an assessment of the situation on the ground with Austin.

The two also discussed the agenda for the next Ukraine Defense Contact Group, which will be held virtually on July 20, and pledged to remain in close contact. 

The call follows the Biden administration's $400 million military aid package announced Friday.

— Amanda Macias

UN to investigate the killing and wounding of children in Ukraine

U.N. Secretary-General Antonio Guterres ordered an investigation into the deaths and injuries of children in Ukraine as Russia's war intensifies.

The findings will be published in the U.N.'s annual "Children and Armed Conflict" global report.

The launch of the new investigations follows warnings from U.N. High Commissioner for Human Rights Michelle Bachelet that her office has mounting evidence that Russian forces carried out potential war crimes.

The Kremlin has denied accusations that its forces target civilians.

— Amanda Macias

Zelenskyy says Europe must prepare for Russia to cut off all gas supplies

Ukrainian President Volodymyr Zelenskyy said Europe needs to prepare for the possibility that Russia cuts off gas supplies.

"Russia has never played by the rules in energy and will not play now unless it sees strength," Zelenskyy said on the Telegram messaging app, according to an NBC News translation.

"Now there can be no doubt that Russia will try not only to limit as much as possible but also to completely stop the supply of gas to Europe," Zelenskyy said, adding, "this is what we need to prepare for now."

Earlier, Russia suspended deliveries of gas to Germany via the Nord Stream 1 pipeline for annual summer maintenance. The planned maintenance of the pipeline has stoked fears that Russia could lengthen the work and further delay gas supplies to Germany.

— Amanda Macias

Lack of rest among Russian troops is plaguing morale on battlefield, UK intelligence says

The U.K. believes that a lack of rest for Russian troops in Ukraine is contributing to poor morale in the ranks.

"The lack of scheduled breaks from intense combat conditions is highly likely one of the most damaging of the many personnel issues the Russian MoD is struggling to rectify amongst the deployed force," the British Ministry of Defense wrote in an intelligence assessment.

Since the Kremlin invaded Ukraine in late February, Russian troops have faced a slew of logistical issues including fuel and food shortages and improper equipment and gear.

— Amanda Macias

Ukrainian troops arrive in UK for military training

The British Ministry of Defense said that Ukrainian soldiers have begun to arrive in the United Kingdom to take part in training alongside British troops.

"The training will give volunteer recruits with little to no military experience the skills to be effective in frontline combat," the British Ministry of Defense wrote on Twitter.

The new U.K.-led program was announced last month when British Prime Minister Boris Johnson visited Kyiv.

— Amanda Macias

Putin expands fast-track Russian citizenship to all Ukraine

As Russian missiles struck a key Ukrainian city, Russian President Vladimir Putin signed a decree expanding a fast-track procedure to make Russian citizenship available to all Ukrainians, yet another effort to expand Moscow's influence in war-torn Ukraine.

Until recently, only residents of Ukraine's eastern Donetsk and Luhansk regions, as well as residents of the southern Zaporizhzhia and the Kherson regions, large parts of which are now under Russian control, were eligible for the simplified passport procedure.

Ukrainian officials haven't yet reacted to Putin's announcement. The decree also applies for any stateless residents currently in Ukraine.

Between 2019, when the procedure was first introduced for the residents of Donetsk and Luhansk, and this year, more than 720,000 people living in the rebel-held areas in the two regions — about 18% of the population – have received Russian passports.

— Associated Press

UN official says there is mounting evidence of Russian war crimes in Ukraine

UN High Commissioner for Human Rights Michelle Bachelet said her office has mounting evidence that Russian forces carried out unlawful killings and summary executions in Ukraine.

Bachelet said that UN investigators have verified the recovery of more than 1,200 civilian bodies from Kyiv.

She added that her office is working to corroborate more than 300 allegations of killings by Russian armed forces in situations that were not linked to active fighting.

The Kremlin has previously denied that its forces have committed crimes against civilians in Ukraine.

— Amanda Macias

Turkey's Erdogan urges Putin to allow the UN to set up a sea corridor for Ukrainian grain exports

Turkish President Recep Tayyip Erdogan told Russian President Vladimir Putin to allow the United Nations to set up a sea corridor for Ukrainian grain exports through the Black Sea, according to a report by Turkish state-owned Anadolu news agency.

For months, Russian warships have blocked Ukraine's ports in the Sea of Azov and the Black Sea.

The blocked food shipments from Ukraine, the world's largest grain supplier, have triggered rising food prices and fueled concerns about global food security.

— Amanda Macias

Volunteers give out food aid in Kramatorsk

Volunteers help to bring food rations to an aid distribution center called "Everything is going to be all right." The assistance program in the city center of Kramatorsk is managed by different non-governmental organizations.

— Miguel Medina | AFP | Getty Images

Death toll from Russian rocket attack on housing block rises to 24

The death toll from a Russian rocket attack on an apartment block in the town of Chasiv Yar in eastern Ukraine over the weekend has risen to 24, Ukraine's state emergency service said, Reuters reported.

The attack in Ukraine's Donetsk region took place on Saturday, causing the building to collapse.

The emergency services said 55 people were helping the rescue effort, which has seen nine people rescued from the ruins of the five-story apartment block.

— Sam Meredith

Russia halts gas flows to Germany via Nord Stream 1

Russia suspended deliveries of gas to Germany via the Nord Stream 1 pipeline for annual summer maintenance works.

The 10-day maintenance works on Europe's single biggest piece of gas import infrastructure are scheduled to run from Monday through to July 21. It has stoked fears that Russia could leverage the planned maintenance to delay or only partially return gas supplies.

It comes at a time when European governments are scrambling to fill underground storage with gas supplies to provide households with enough fuel to keep the lights on and homes warm during winter.

"We cannot rule out the possibility that gas transport will not be resumed afterwards for political reasons," Klaus Mueller, the head of Germany's energy regulator, told CNBC last week.

Kremlin spokesperson Dmitry Peskov has previously dismissed claims that Russia was using oil and gas to exert political pressure over Europe, according to Reuters.

— Sam Meredith

Russians shell Kharkiv, residents told to stay indoors to avoid 'extreme' danger

Russian troops are shelling the city of Kharkiv with multiple launch rocket systems, with local residents being urged not to go outdoors amid "extremely dangerous" conditions.

Kharkiv Regional Military Administration's Head Oleh Synyehubov issued a warning on Telegram in which he said "Russian occupiers have opened fire, reportedly with multiple launch rocket systems."

"Attention! Residents of Kharkiv and Kharkiv Region, please do not stay outdoors unless absolutely necessary. It is extremely dangerous. All services are responding quickly and working at the scene," Synyehubov said.

Ukraine's armed forces have already reported on Monday morning that Russian missile strikes were targeting Kharkiv, Ukraine's second-largest city, with a school among the buildings being destroyed.

— Holly Ellyatt

Death toll from Russian rocket attack on apartment block rises to 18

The death toll from a Russian rocket attack that hit a five-storey apartment block in the town of Chasiv Yar in Donetsk in eastern Ukraine has risen to 18 on Monday.

Search and rescue teams are still racing to reach survivors in the rubble, the emergency services said. Images published on Sunday showed teams using their hands to try to unpick the rubble and reach people trapped in the ruins of the building.

"Rescuers have recovered a body of another victim from under the rubble of a 5-storey apartment block destroyed in the missile strike on the city of Chasiv Yar," the report on Facebook stated Monday.

"A total of 18 civilians were found dead. Six civilians were rescued from under the rubble. A total of 138 tonnes of destroyed structures were dismantled. Rescue works are underway."

A further update stated that two more men had been rescued from the rubble in the ongoing rescue operation.

— Holly Ellyatt

Russia launches a wave of attacks in eastern Ukraine

Russian forces have launched a wave of attacks on various cities in the east of the country and look like they're preparing to intensify their assaults, Ukraine's general staff said on Monday.

Russian forces have particularly intensified their assaults around Ukraine's second-largest city Kharkiv with artillery, rocket launchers and tanks deployed in the city and surrounding areas, Oleksandr Shtupun, the spokesman for the general staff of Ukraine's armed forces, said on Facebook on Monday.

Shtupun said that in the Donetsk direction, "there are signs of enemy units preparing to intensify combat operations in the Kramatorsk and Bakhmut directions" and that in the area of Sloviansk — a city of the new frontline in Donetsk — various settlements to the north and northwest had been shelled with barrel and jet artillery.

The nearby city of Kramatorsk to the south had not seen active operations, Shtupun said, but towns between Sloviansk and Severodonetsk — the border area between Russian-occupied Luhansk and Donetsk — have been shelled with barrel artillery, Shtupun said.

—Holly Ellyatt

Le Maire: Russia cutting gas to Europe is one of the key scenarios

French Finance Minister Bruno Le Maire, speaking Sunday to CNBC's Charlotte Reed at the Rencontres Economiques event in Aix-en-Provence, discusses the possibility of Russia shutting off the gas taps to Europe.

"I think that this is one of the key scenarios and we have to be prepared for all options. That's the responsibility of all politicians to take into account the geopolitical situation," he said.

—Matt Clinch

In pictures: Rescuers search for victims and survivors of apartment block attack

EDITOR'S NOTE: This article contains an image of search and rescue teams removing human remains from the Chasiv Yar apartment block that was struck by Russian forces.

Search and rescue operations are continuing in Chasiv Yar to find victims and survivors of a Russian missile strike on an apartment block. The town lies southeast of Kramatorsk in Donetsk, eastern Ukraine.

At least 15 people died in the attack and the death toll is likely to rise, Ukraine's President Volodymyr Zelenskyy said on Sunday night.

Several dozen people are believed to be trapped under the rubble and residents have been displaced after losing their homes.

Russia has repeatedly said it does not target civilians despite numerous occasions where civilian infrastructure has been hit during the war.

— Holly Ellyatt

Russia is a 'terrorist state,' Zelenskyy says after apartment block attack

Ukraine's President Volodymyr Zelenskyy has said the death toll is likely to rise following a Russian attack on an apartment block in Donetsk at the weekend. 

"I have been receiving reports all day today from the city of Chasiv Yar in Donetsk region," Zelenskyy said in his late night address last night. "There are 15 names on the list of the dead and, unfortunately, this is not the final number."

"It was a missile strike. And everyone who gives orders for such strikes, everyone who carries them out in our ordinary cities, in residential areas, kills absolutely deliberately," the president added.

Zelenskyy said Ukraine would seek to punish those responsible for the attack, and any others involved in the invasion of Ukraine.
 
"Since the beginning of this invasion, Ukrainian law enforcement officers have been doing everything necessary to record the crimes of the occupiers and to collect evidence," he said, adding that Russia should be deemed a terrorist state:

"Russian terror has long crossed the line beyond which it became obvious to many in the civilized world that it is a matter of global security to punish Russia, a terrorist state, for everything it has done against Ukraine and the international legal order."

Russia has repeatedly said it does not target civilians despite numerous occasions where civilian infrastructure has been hit during the war.

— Holly Ellyatt

Russia is not taking an 'operational pause,' Zelenskyy says

From Ukraine's perspective, Russia is not taking an "operational pause" from heavy fighting in the Donbas in eastern Ukraine, the country's president said on Sunday night.

"In the past week, there was a lot of talk about the alleged 'operational pause' in the actions of the occupiers in Donbas and other parts of Ukraine," Zelenskyy said in his nightly address. "Thirty-four airstrikes by Russian aircraft in one past day is an answer to all those who invented this 'pause'."

Zelenskyy's comments come after military analysts said Russia appeared to have made few advances in the Donbas last week; the capture of the entire region is one of Russia's stated war aims.

According to analysts, Russian forces are likely regrouping following heavy fighting in order to capture Luhansk, a region making up half of the Donbas, along with Donetsk, in which Russian forces are now trying to advance.

But there had been no pause for Ukraine, Zelenskyy said, noting that "the Ukrainian army is holding on, holding firm and repelling assaults in various directions." 

"But, of course, a lot still needs to be done so that Russian losses become such that there will really be a pause. Moreover, the pause is not before new offensives of the occupiers, but before their escape from our Ukrainian native land. And I am grateful to all our fighters who ensure that this time is approaching."

— Holly Ellyatt

At least 15 killed after Russian strike on apartment block in Donetsk

At least 15 people have been killed and dozens are still trapped after Russian rockets hit a five-storey apartment block in Ukraine's Donetsk region on Saturday, causing the building to collapse.

Donetsk region Governor Pavlo Kyrylenko said on Telegram that at least 34 people could be trapped under the rubble of the high-rise building in Chasiv Yar, which was struck by Russian rockets late on Saturday.

He said yesterday that five people had been rescued with emergency services communicating with others trapped under the rubble. According to various estimates, there may be another 24 people trapped in the ruins of the building, including a 9-year-old child, Kyrylenko said.

"Rescuers of the State Emergency Service dismantled about 99 tons of destroyed elements of the building.
The rescue operation is ongoing," he commented.

Andriy Yermak, chief of staff to Ukraine's president, said on Twitter that Russia "should be on the list of state sponsors of terrorism" following another attack on civilian infrastructure.

Russia has repeatedly denied targeting civilians despite mounting evidence to the contrary and investigators continue to gather evidence of war crimes in Ukraine.

— Holly Ellyatt