This has been CNBC's live blog covering updates on the war in Ukraine. [Follow the latest updates here.]

In a tough weekend for Ukraine, Kyiv confirmed on Sunday that Russian forces have taken control of the city of Lysychansk, and by doing so, seized the entire Luhansk province.

The capture of the city, from which Ukrainian forces retreated to avoid being encircled, marks another significant step for Russia, which aims to control the entire eastern Donbas region.

Ukrainian President Volodymyr Zelenskyy has vowed that Ukrainian forces will return to Lysychansk and take back the city.

Russian forces appeared to have wasted no time in turning their firepower on cities within the neighboring Donetsk province, which also makes up a significant part of the Donbas. The governor of the region said several key cities had experienced heavy shelling on Sunday.

Ukraine needs $750 billion for its recovery plan, prime minister says

Ukraine will need a massive $750 billion for its recovery following Russia's invasion, the county's Prime Minister Denys Shmyhal said while speaking to international leaders in Switzerland gathered for the Ukraine Recovery Conference.

Shmyhal also said that Russia's invasion has so far resulted in more than $100 billion in damage to Ukrainian infrastructure.

Country leaders, private sector and NGO representatives attended the conference to discuss a sort of "Marshall Plan" to rebuild Ukraine.

President Zelenskyy, who spoke to the conference attendees via video call, warned that there was "really colossal" work needed to reconstruct the areas that have already been taken back from Russian troops. In addition to that, "we will have to free over 2,000 villages and towns in the east and south of Ukraine," he said.

Sloviansk, in Donetsk, prepares for Russian onslaught

The eastern Ukrainian city of Sloviansk in Donetsk is readying for a major battle after Russian forces captured neighboring Luhansk province.

"Everyone knows that there will be a huge battle in Sloviansk," one Ukrainian soldier told the Associated Press. Soldiers defending the city told the AP that they are severely outgunned by the Russians.

The city, home to roughly 100,000 people before the war, was captured by pro-Russian fighters in 2014 and held for three months before being retaken by Ukrainian forces. For many in the city, the war has been going on since then. Roughly three-quarters of Sloviansk's population has fled since late February, and city officials are urging remaining civilians to evacuate.

— Natasha Turak

Moscow vows to reciprocate after Bulgaria expels 70 Russian diplomats

Moscow will respond in kind to Bulgaria's expulsion of 70 of its diplomats, Russian Foreign Minister Sergei Lavrov said following the largest-ever expulsion of Russians from the EU country. The Russian embassy staff were ordered to leave Bulgaria by Monday.

While the two have historically close ties, Bulgaria is a member of NATO and its government took a strong stance backing sanctions against Russia for its invasion of Ukraine. Moscow responded by cutting gas supplies to the country in April.

"Anyone who works against the interests of Bulgaria will be called to go back to the country from which they came," Bulgarian Prime Minister Kiril Petkov said. Petkov has accused Moscow of launching a "hybrid warfare" campaign against his government.

— Natasha Turak

Putin congratulates Russian troops for 'liberating' Luhansk region

President Vladimir Putin congratulated Russian troops on "liberating" Ukraine's eastern Luhansk province after several weeks of brutal fighting. A huge proportion of the area's infrastructure, including residential buildings, has been destroyed.

Speaking on television with Defense Minister Sergei Shoigu, Putin said that the troops who fought in Luhansk should rest but that other troops should keep fighting, according to a Reuters translation.

Ukrainian forces have withdrawn from the majority of the area, although President Volodymyr Zelenskyy has pledged to win back the lost territory. Russian forces are now expected to turn their focus to neighboring Donetsk, which together with Luhansk makes up the Donbas region, Moscow's top territorial priority.

— Natasha Turak

U.S. ambassador to China takes rare opportunity to slam Russia

Washington's ambassador to China spoke out against Russia during a forum and criticized China's foreign ministry for repeating Russian "propaganda."

Ambassador Nicholas Burns called Russia's war in Ukraine "the greatest threat to global world order," and said he hoped China's government would stop spreading Russian rhetoric that blamed NATO for the crisis.

"I hope foreign ministry spokespersons would also stop telling lies about American bioweapons labs, which do not exist in Ukraine," Burns said during the event entitled the "World Peace Forum," hosted by Tsinghua University.

Burns was speaking among top French, British, Chinese and Russian diplomats to an audience of Chinese and other foreign diplomats, students and professors. The event was organized as a talk among representatives of the five permanent U.N. Security Council member states.

Also speaking at the forum, U.K. ambassador Caroline Wilson said, "If Russia has its way, we would have global anarchy." Russia refutes the West's criticisms. The ambassadors' comments were rare for China, a country that broadly stifles dissent.

China has refrained from condemning Russia for its invasion of Ukraine both in world politics and in media. Much of its media takes a narrative that places blame on the West and criticizes sanctions imposed on Russia.

— Natasha Turak

Russia will now shift focus to Donetsk, Luhansk governor says

Russia has captured Ukraine's eastern Luhansk region and will now turn its focus to neighboring Donetsk, Luhansk's regional governor Serhiy Haidai said.

The governor expects Russian forces to concentrate their attacks on Sloviansk, a city with a pre-war population of roughly 100,000 that was the first to be seized by Russian-backed forces in 2014. It was then retaken by Ukrainian troops.

Haidai also named the town of Bakhmut as a key target for Russia.

Luhansk and Donetsk, known collectively as the Donbas, has been the site of sporadic fighting between Ukrainian and pro-Russian troops for many years. Moscow has called capturing the Donbas an "unconditional priority."

Ukrainian President Volodymyr Zelenskyy has vowed that Ukraine will take back its land seized by Russia.

— Natasha Turak

Russia's 'grinding and attritional' tactics in the Donbas unlikely to change, UK says

Britain's Ministry of Defense has said that Russian forces, having seized the Luhansk province in the Donbas after weeks of intense shelling, are likely to employ the same tactics to seize Donetsk, which makes up the rest of the eastern region of Ukraine.

"The fight for the Donbas has been grinding and attritional and this is highly unlikely to change in the coming weeks," the ministry said in its latest intelligence update on Twitter on Monday.

"Russia's Ministry of Defence had earlier claimed to have completed the encirclement of Lysychansk and secured full control of the city," the U.K. said of the weekend's developments in the Luhansk. It added that "Russia's focus will now almost certainly switch to capturing Donetsk Oblast, a large portion of which remain under the control of Ukrainian forces."

The U.K. noted that the invasion is continuing to have a devastating impact on Ukraine's agricultural sector, causing major disruption to the supply chains of seed and fertilizer which Ukrainian farmers rely on.

"Russia's blockade of Odesa continues to severely constrain Ukraine's grain exports. Because of this, Ukraine's agricultural exports in 2022 are unlikely to be more than 35% of the 2021 total."

"Following its retreat from the Black Sea outpost of Snake Island, Russia misleadingly claimed that 'the ball is now in Ukraine's court' in relation to improving grain exports. In reality, it is Russia's disruption of Ukraine's agricultural sector which continues to exacerbate the global food crisis," the ministry concluded.

— Holly Ellyatt

89 Ukrainian athletes and coaches have been killed during the war, Zelenskyy says

As many as 89 Ukrainian athletes and coaches have been killed since Russia invaded Ukraine, the country's president told Thomas Bach, the president of the International Olympic Committee, on Sunday.

President Zelenskyy described how the country's sportsmen and women and have been affected by the war, with thousands of Ukrainian athletes unable to train, hundreds of sports facilities destroyed, and a large number killed in the fighting. 

"Many Ukrainian athletes joined the ranks of the Ukrainian Armed Forces to defend our country, to defend it on the battlefield. Some 89 athletes and coaches have been killed in hostilities. Thirteen were captured and are in Russian captivity," he told Bach.

The IOC has offered a new support package for Ukrainian Olympians. The IOC's Bach said his position was unchanged when it comes to Russian and Belarusian athletes being barred from participating in some international competitions held under the auspices of the IOC.

"The time has not yet come to lift such a ban," Bach said.

— Holly Ellyatt

Russian forces turn firepower on Donetsk

Russian forces have turned their attention to capturing more parts of the Donetsk region of the Donbas, with the province coming under heavy shelling on Sunday, according to the head of the province.

Pavlo Kyrylenko, the head of the Donetsk oblast (or province), said it was a "difficult Sunday in Donetsk region [with] rocket strikes and shelling throughout the region."

He said the area's largest cities — Kramatorsk and Sloviansk — were the most affected. Six people, including one child, were killed in Sloviansk after what Kyrylenko described as "massive shelling during the day." Nineteen people were injured and multiple residential buildings were damaged.

Kramatorsk, meanwhile, was shelled by a Russian "Smerch" multiple launch rocket system, he said. "During the day they damaged a hotel and residential complex, in the evening they destroyed a road, targeted a school and the territory of a kindergarten and a clinic," Kyrylenko said on Telegram in a post accompanied by images of heavily damaged and destroyed residential buildings.

The shelling in Kramatorsk left one person injured while in a residential area another person was killed.

"In just one day, the Russians killed at least 7 civilians and wounded at least 20 in Donetsk region," Kyrylenko said. CNBC was not able to immediately verify the information.

— Holly Ellyatt

'We will return' to captured Lysychansk, Zelenskyy says

Ukraine's President Zelenskyy conceded on Sunday that his forces have had to retreat from the city of Lysychansk in the Luhansk province in the eastern Donbas region, but vowed to return to the area.

"If the commanders of our army withdraw people from certain points at the front, where the enemy has the greatest advantage in fire power, and this also applies to Lysychansk, it means only one thing," he said in his nightly video address.

"That we will return thanks to our tactics, thanks to the increase in the supply of modern weapons."

Zelenskyy said Russia had enough multiple rocket launch systems to destroy "city after city in Ukraine" and that the reality is that "they have gathered most of their firepower in Donbas."

The president defended the decision to prioritize lives over land, noting: "The fact that we protect the lives of our soldiers, our people, plays an equally important role. We will rebuild the walls, we will win back the land, and people must be protected above all else."

Russia claimed it had captured Lysychansk on Sunday, a development that was later confirmed by Ukraine. Russian forces now control the Luhansk region and are expected to now focus on capturing more territory in Donetsk. Russia has said its main aim in the war is to "liberate" the Donbas region in east Ukraine where two breakaway pro-Russian, self-styled "republics" are located.

— Holly Ellyatt