This is CNBC's live blog tracking developments on the war in Ukraine. See below for the latest updates.
Signs of tension have emerged between allies Russia and China, as Putin acknowledged his Chinese counterpart Xi Jinping's "questions and concerns" about Russian operations in Ukraine during the leaders' first in-person meeting since the war began on Feb. 24.
There are reports of mass graves outside the cities recently recaptured by Ukrainian forces after months of Russian occupation, Ukrainian officials and international media present on the scene have said.
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Meanwhile, Berlin is taking control of Russian energy giant Rosneft's German operations, citing the need to protect the continuity of business operations and ensure its energy security.
Two NASAMS air defense systems will arrive in Ukraine by mid-November
The Pentagon updated its timeline for the transfer of two National Advanced Surface-to-Air Missile Systems (NASAMS) to Ukraine, saying they would arrive within two months, or by mid-November.
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"We're tracking that two NASAMS are expected to be delivered within the next two months or so," said Pentagon press secretary Brigadier Gen. Patrick Ryder.
"These defensive systems will further contribute to protecting Ukrainians from enemy air threats, including aircraft, unmanned aerial vehicles and missiles."
The NASAMS is one of the most highly anticipated weapons systems that has been committed to the Ukrainian military thus far in the war.
Developed by Raytheon and Norway's Kongsberg, it is orders of magnitude more advanced than the Russian-made air defense systems that Ukraine has used in the past, notably the S-300.
It also represents a major step for Ukraine's military toward a longer-term cooperation with Western allies.
NASAMS "is a NATO system, so for us it's important to start to help the Ukrainians transition their air defense systems from what is a now a Soviet-type system, to introduce some of this modern technology," a senior Defense Department official said in July.
-- Christina Wilkie
'The president is not going to let up,' White House says on bringing Brittney Griner and Paul Whelan home
The Biden administration is not going to let up in its efforts to bring WNBA star Brittney Griner and former U.S. Marine Paul Whelan home, a White House spokesman said.
"Discussions are ongoing. I think Karine said it really well yesterday, sadly we don't have an agreement to tell you about," national security spokesman John Kirby told reporters at the White House.
"We made a serious offer," Kirby said, referencing the Biden administration's offer for the release of the two U.S. citizens in Russian custody.
"What I can tell you for sure is the president is not going to let up," he added.
— Amanda Macias
Ukraine is consolidating gains in the north, making 'forward movements' in the south, according to latest U.S. assessment
The latest U.S. assessment of the war in Ukraine is that Ukraine is setting the pace of the war both in the north and south, but that its momentum is manifesting differently in the two different theaters.
"In the north, what we assess is that the Ukrainians are consolidating their gains after taking back significant territory, and that the Russians are attempting to shore up their defensive lines after having been pushed back," said Pentagon press secretary Air Force Brig. Gen. Pat Ryder in a briefing with reporters.
"In the south, the Ukrainians continue to make what we would assess as deliberate calculated forward movements, as the Russians continue to try to hold that line," he added.
Ryder declined to speculate on any timeline for an end to the conflict. "The only thing that could shorten it is if the Russians decided to do the right thing and withdraw their forces from occupying Ukraine," he said.
-- Christina Wilkie
About 16 million people in Ukraine are in need of water, sanitation and hygiene assistance
About 16 million people in Ukraine urgently need water, sanitation and hygiene assistance, the United Nations estimates.
"These include internally displaced people in collective centers and host communities, in addition to communities affected by hostilities-related damages to systems and limitations in water treatment consumables," the U.N. wrote.
The U.N. warned that there is an elevated risk of sanitation and hygiene-related diseases.
The Kremlin has previously denied that its forces target civilian infrastructure.
— Amanda Macias
U.S. delegation will meet with Ukrainians at U.N. General Assembly next week, no plans to meet with Russians
U.S. Ambassador to the United Nations Linda Thomas-Greenfield said the Biden administration will meet with Ukrainian officials on the sidelines of the United Nations General Assembly next week.
The high-level meeting of the 193 members of the United Nations General Assembly begins on Sept. 20 in New York City.
Thomas-Greenfield declined to elaborate further on the meetings President Joe Biden and Secretary of State Antony Blinken would have.
She said the Biden administration does not now have plans to meet with the Russian delegation at the United Nations.
"They have not indicated that they have an interest in diplomacy. What they're interested in is continuing to raise this unprovoked war on Ukraine," she told reporters during a press briefing at the United Nations.
— Amanda Macias
More than 14.5 million people in Ukraine are in need of health assistance, U.N. says
More than 14.5 million people in Ukraine are in need of health assistance, according to a United Nations estimate.
"Access to health care continues to be severely impacted by security concerns, restricted mobility, broken supply chains and mass displacement," the U.N. wrote in a new report.
Since Russia invaded Ukraine on Feb. 24, there have been at least 550 attacks on vital health services in the country, the World Health Organization's Surveillance System for Attacks on Health Care estimates.
The organization reports that health care facilities were damaged 469 times, ambulances were targeted in 75 cases and at least 144 attacks affected crucial medical supplies. The group also estimated that attacks on health services led to at least 100 deaths and 129 injuries.
The Kremlin has previously denied that it targets civilian infrastructure like hospitals, schools and apartment buildings.
— Amanda Macias
U.S. ambassador to the U.N. slams Russia's weaponization of food
U.S. Ambassador to the United Nations Linda Thomas-Greenfield slammed Russia's war in Ukraine and Moscow's decision to weaponize food supply.
"Before the war, Russia and Ukraine accounted for almost a quarter of global grain exports. But now Ukraine's once rolling wheat fields have become battlefields. This weaponization of food has had global ripple effects. Russia's war has exacerbated this crisis," Thomas-Greenfield said at the United Nations.
"The impacts on wheat, food, oil, and fuel are being felt by all of us. The answer to all of the questions is simple – end the war – end the unprovoked attack on Ukraine and that will get us out of part of this situation," she added.
Thomas-Greenfield said that Ethiopia, northeast Nigeria, Yemen and South Sudan are proving to be the most vulnerable countries to food insecurity.
— Amanda Macias
Four vessels set to depart Ukraine carrying 69,600 metric tons of agricultural products
The organization overseeing the export of agricultural products from Ukraine said it has approved four vessels to leave the besieged country.
The Joint Coordination Center, an initiative of Ukraine, Russia, the United Nations and Turkey, said that the vessels are carrying 69,600 metric tons of grain and other food products.
The ships are expected to depart tomorrow and are destined for Germany, Romania, Greece and Egypt.
Since Ukraine's ports were reopened, more than 2.2 million metric tons of grain and other food products have been exported.
— Amanda Macias
More than 400 bodies found in mass graves in Izium, Zelenskyy says
EDITORS NOTE: This post shows graphic content of mass graves uncovered near Izyum, Ukraine.
Ukrainian President Volodymyr Zelenskyy said that more than 400 bodies have been discovered in mass grave sites in the city of Izium.
"More than 400 bodies were found at the mass burial site in Izyum with signs of torture. Children, those killed as a result of missile attacks, warriors of the Armed Forces of Ukraine," Zelenskyy said in English on the Telegram messaging app.
"Russia leaves only death and suffering. Murderers. Torturers. Deprived of everything human. You won't run away. You won't hide. Retribution will be justly dreadful. For every Ukrainian, for every tortured soul," he added.
The Kremlin has previously denied that its forces target and kill civilians, which is a violation of international humanitarian law.
— Amanda Macias, Adam Jeffery and Getty Images
Ukraine war has pushed 70 million people closer to starvation, UN says
Russia's invasion of Ukraine and the ensuing nearly seven months of war have thrown millions of people around the world into food insecurity and brought many of those closer to starvation, the head of the U.N.'s World Food Program warned.
"What was a wave of hunger is now a tsunami of hunger," WFP chief David Beasley said, noting that the number of people suffering from acute food insecurity had doubled since the Covid-19 pandemic first hit. The war in Ukraine has sent food inflation soaring, as Russian warships have largely blocked Ukraine's vital Black Sea ports, through which huge proportions of the world's grain and other staple food products are shipped.
Beasley said that the surge in costs of food, fuel and fertilizer has brought 70 million people closer to starvation.
Turkey in July brokered an agreement that enabled Ukrainian grain to be exported from three Black Sea ports that had been blocked by Russia, and efforts are continuing to get more produce out to markets, as well as Russian fertilizer, the export of which is hampered by Western sanctions.
Still, Beasley said, "there is a real and dangerous risk of multiple famines this year."
— Natasha Turak
Milley and national security advisor Jake Sullivan hold calls with Ukrainian counterparts
Chairman of the Joint Chiefs of Staff Gen. Mark Milley and national security advisor Jake Sullivan spoke with their Ukrainian counterparts.
"They discussed the unprovoked and ongoing Russian aggression in Ukraine and international support for the Ukrainian armed forces," according to a Pentagon readout of the call with Ukrainian Armed Forces Gen. Valery Zaluzhny and Ukraine's Andriy Yermak.
The call comes as Ukrainian forces carried out lightning advances in the country's east and south and as the Biden administration readied a new security assistance package.
The latest package, the 21st such installment, is worth approximately $600 million.
— Amanda Macias
Kyiv criticizes Germany for failing to send the heavy weapons it promised
Ukraine's relations with Germany have soured this week, with Kyiv asking why Berlin reneged on its promise to provide heavy weaponry.
Tensions over Germany's provision of Leopard tanks and infantry fighting vehicles to Ukraine — or lack thereof — came to a head this week when Ukraine's Foreign Minister Dmytro Kuleba publicly asked why Berlin was backtracking on a pledge made to send these weapons to Ukraine.
"Disappointing signals from Germany while Ukraine needs Leopards and Marders now — to liberate people and save them from genocide," Kuleba said on Twitter, adding that there was "not a single rational argument on why these weapons can not be supplied, only abstract fears and excuses."
"What is Berlin afraid of that Kyiv is not?" he added.
Read the full story here.
— Holly Ellyatt
Russian mercenary firm Wagner Group is recruiting convicts for Ukraine war
Russian mercenary firm Wagner Group is recruiting criminal convicts and has been doing so since at least July, Britain's Ministry of Defense said in its daily intelligence update posted via Twitter.
"Kremlin-linked Russian private military company Wagner Group has been conducting a campaign to recruit Russian convicts for service in Ukraine since at least July. Prisoners have been offered commutation of their sentences as well as cash incentives," the ministry wrote.
The Wagner Group has been notorious for its fighting on behalf of Russian interests in places like Libya, Syria, and parts of Sub-Saharan Africa. The Kremlin denies links to the group.
The group's recruitment campaign has been "reinvigorated," the report added, citing a recently posted video "highly likely showing Wagner owner Yevgeny Prigozhin making a recruitment pitch to prisoners."
Prigozhin in the video says he is only seeking "fighters for assault units."
This, in addition to Russia's military academies shortening the training time for cadets and moving their graduation dates forward, "suggests that two of the most critical shortages within the military manning crisis are probably combat infantry and junior commanders," Britain's Defense Ministry wrote.
— Natasha Turak
Berlin takes control of Rosneft's German unit
The German government is taking control of Russian oil and gas giant Rosneft's operations in Germany, its Ministry for Economic and Climate Affairs announced.
Germany's federal network agency BNetzA will take over the local units — RN Refining & Marketing GmbH and Rosneft Deutschland GmbH — which make up roughly 12% of Germany's oil processing capacity, the ministry said.
In a statement, the German economy ministry said:
"The continuation of the business operations of the affected refineries was in danger due to the ownership of the companies. Central critical service providers such as suppliers, insurance companies, IT companies and banks, but also customers, were no longer willing to work with Rosneft."
The move is "a further step to assuring our energy security," state secretary Jorg Kukies wrote in a tweet.
— Natasha Turak
Reports of mass grave site outside recaptured city of Izium
A site of mass burials has been found in a forest near the recently liberated city of Izium, the Associated Press reported, revealing the latest iteration of a well-documented pattern of actions suspected to have been carried out by Russian forces that occupied the region for more than six months.
The site was marked by wooden crosses and a marker on a larger grave said 17 Ukrainian soldiers had been buried there. Ukrainian forces recaptured the city in an operation that saw thousands of Russian forces retreat.
"We haven't counted them yet, but I think there are more than 25 or even 30," Oleg Kotenko, a Ukrainian government official, told the AP.
The news agency quoted a local resident, Sergei Gorodko, who said that scores of adults and children killed in a Russian strike on a residential building were among the hundreds of people buried in individual graves.
Russia's Foreign Ministry has not yet commented publicly, and has not responded to a CNBC request for comment.
— Natasha Turak
U.S. announces new $600 million security assistance package for Ukraine
The Biden Administration has approved another arms package worth $600 million to further assist Ukraine in its ongoing battle against Russia, according to the Department of Defense.
The package is said to include additional ammunition for High Mobility Artillery Rocket Systems (HIMARS), artillery rounds, vehicles, and counter-unmanned aerial systems, among other equipment.
It marks the 21st drawdown of equipment from Department of Defense inventories since August last year.
So far, Washington has sent more than $15.1 billion in security assistance to Ukraine since the beginning of Russia's unprovoked war in Ukraine.
— Natalie Tham
Putin acknowledges China's concerns over Ukraine in sign of friction
Russian President Vladimir Putin said he understood China's Xi Jinping had concerns about the situation in Ukraine, a surprise acknowledgement of friction with Beijing over the war after a week of stunning Russian losses on the ground.
Since Russia's invasion, China has trod a careful line, criticizing Western sanctions against Russia but stopping short of endorsing or assisting in the military campaign.
"We highly value the balanced position of our Chinese friends when it comes to the Ukraine crisis," Putin told Xi at their first meeting since the war began.
"We understand your questions and concern about this. During today's meeting, we will of course explain our position."
Xi did not mention Ukraine in his public remarks, nor was it mentioned in a Chinese readout of their meeting, which took place in Uzbekistan on the sidelines of a regional summit.
Beijing's support is widely seen as essential for Moscow, which needs markets for its energy exports and sources to import high tech goods as it faces sanctions imposed by the West.
The last time the two men met they signed a "no limits" friendship agreement between their two countries. Three weeks later, Russia invaded Ukraine.
The Russian president's comments suggested a Chinese shift towards a more critical stance, in private at least. Ian Bremmer, political science professor at Columbia University, said they were the "first public sign of Putin recognizing pressure to back down."
— Reuters
Read CNBC's previous live coverage here:
Ukraine medic tells U.S. Congress of 'hell' in Russian captivity; Putin acknowledges China pressure