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

Ukraine's President Volodymyr Zelenskyy has warned that "a really difficult road" lies ahead for Ukraine as Russia makes incremental advances in the east of the country.

Meanwhile in Istanbul, a high-stakes meeting has begun among Ukraine, Turkey, Russia and the United Nations, focusing on efforts to restart Ukrainian grain exports.

Andriy Yermak from Zelenskyy's office said on his Telegram channel that the parties will discuss sea corridors for the export of grain, along with security issues. For months, Russian war ships have blocked Ukrainian ports on the Sea of Azov and the Black Sea.

Back in Ukraine, anti-Russian sentiment is rife in occupied parts of the country, Britain's Ministry of Defense noted on Wednesday, with Russian and pro-Russian officials (called collaborators by Ukraine) being targeted. A Moscow-installed mayor in Velykyi Burluk in the Kharkiv region was killed in a car bombing on Monday.

Ukraine, U.N., Russia and Turkey to discuss sea corridors for grain exports next week following talks

Russia and Ukraine are slated to meet again in Turkey next week following talks that aim to free up grain exports, Turkish Defense Minister Hulusi Akar said in a statement.

Delegations from Russia, Ukraine, Turkey and the United Nations met in Istanbul earlier.

"We will try to reach a conclusion by carrying out this in coordination with the UN. In this sense, it was agreed that the Ukrainian and Russian delegations should meet again in Turkey next week," Akar said in a statement.

UN Secretary-General Antonio Guterres said in a press conference that the meeting was a "critical step forward" in the safe and secure export of Ukrainian food products through the Black Sea.

For months, Russian warships have blocked Ukrainian ports on the Sea of Azov and the Black Sea.

— Amanda Macias

U.S. welcomes EU decision to impose sanctions on Russian shipments to Kaliningrad

The Biden administration welcomed the European Union's decision to implement economic sanctions on Russia and its shipments to and from Kaliningrad.

Kaliningrad, sandwiched between Lithuania and Poland, depends on Lithuania and Belarus to conduct transit traffic between the enclave and mainland Russia.

"We applaud European Union member states, including Lithuania, for enforcing sanctions measures fully in accordance with EU guidance," wrote State Department spokesman Ned Price in a statement.

"It is important to note that there is not now and there never has been a so-called blockade of Kaliningrad. Using a variety of routes, passengers continue to transit between mainland Russia and Kaliningrad, as do all humanitarian shipments and most other goods," Price added.

In June, Lithuania announced it would halt entry by rail of all EU-sanctioned goods coming from Russia into Kaliningrad.

Russian Foreign Ministry spokeswoman Maria Zakharova said Lithuania's actions in the Russian enclave of Kaliningrad will trigger retaliatory measures.

— Amanda Macias

More than 5.8 million refugees have fled Ukraine, UN says

More than 5.8 million people have fled across Ukraine's borders to other locations in Europe since Russia invaded in February, according to the latest data compiled by the United Nations.

Of that total, more than 3.6 million people have registered for temporary refugee protection or similar safeguards in Europe.

"The escalation of conflict in Ukraine has caused civilian casualties and destruction of civilian infrastructure, forcing people to flee their homes seeking safety, protection and assistance," UN researchers wrote in a report.

"Millions of refugees from Ukraine have crossed borders into neighboring countries and many more have been forced to move inside the country," the report added.

Here's a look at where Ukrainian refugees have fled:

— Amanda Macias

U.S. Defense Secretary Austin and Dutch counterpart discuss Ukraine at Pentagon

U.S. Secretary of Defense Lloyd Austin thanked his Dutch counterpart for supplying Ukraine with military aid and for supporting joint U.S.-EU sanctions against Russia during a visit to the Pentagon.

"The Netherlands has heeded Ukraine's calls for defensive and lethal equipment, especially in high-priority areas such as artillery and coastal defense," Austin said, according to a Pentagon readout of the meeting with Netherlands Minister of Defense Kajsa Ollongren.

"Your government has also helped bolster NATO's eastern flank by sending forces to Lithuania, Slovakia, and Romania, and as you've heard me say before, I've never seen NATO more united than it is right now," Austin added.

The visit follows last month's NATO Summit in Madrid, Spain where the 30-member bloc approved the expansion of the military alliance to include Sweden and Finland.

"We also welcome your government's support for E.U. sanctions on Russian energy to impose further economic cost on Moscow and I want to thank you for your leadership in moving toward your NATO commitments and for increasing your defense budget to invest in modern and relevant capabilities," Austin said, according to the readout.

— Amanda Macias

UN expert to visit Poland and Belarus to view Ukrainian refugee conditions

The U.N. will dispatch an expert to Poland and Belarus to assess the condition of Ukrainian migrants and refugees in those countries.

U.N. expert Felipe Gonzalez Morales is slated to visit Poland's border areas with Belarus and Ukraine, including crossing points, guard posts, registration and processing centers, asylum reception centers, immigration detention facilities and other temporary reception facilities.

Gonzalez Morales, the U.N.'s special rapporteur on the human rights of migrants, will also meet with Belarusian governmental authorities, U.N. agencies, civil society organizations and refugees.

Since Russia invaded Ukraine in late February, more than 5.8 million refugees have fled Ukraine, according to data compiled by the United Nations.

Gonzalez Morales will present his observations and recommendations to the Human Rights Council next year.

— Amanda Macias

Gazprom casts doubt on pipeline’s quick return to full flow

Russian energy giant Gazprom appeared to cast doubt on the prospects of quickly restoring the flow of natural gas to full capacity through a major pipeline to western Europe.

Gazprom last month reduced the gas deliveries through Nord Stream 1 to Germany by 60%. The state-owned gas company cited technical problems involving a part that partner Siemens Energy sent to Canada for overhaul and couldn't be returned because of sanctions imposed over Russia's invasion of Ukraine.

The Canadian government said over the weekend that it would allow the gas turbine that powers a compressor station to be delivered to Germany, citing the "very significant hardship" that the German economy would suffer without a sufficient gas supply to keep industries running and generate electricity.

In a statement on Twitter, Gazprom said it "does not possess any documents that would enable Siemens to get the gas turbine engine ... out of Canada." It added that "in these circumstances, it appears impossible to reach an objective conclusion on further developments regarding the safe operation" of a compressor station at the Russian end of the pipeline.

Nord Stream 1 runs under the Baltic Sea is Germany's main source of Russian gas, which recently has accounted for about 35% of the country's total gas supply. Gas is usually sent onward to other European countries as well.

— Associated Press

U.S. calls on Russia to halt forced deportations of Ukrainians, citing possible war crimes

The Biden administration called on Russia to immediately halt systematic filtration operations and forced deportations in Russian-controlled areas of Ukraine, citing the possibility of war crimes.

"The unlawful transfer and deportation of protected persons is a grave breach of the Fourth Geneva Convention on the protection of civilians and  is a war crime," Secretary of State Antony Blinken wrote in a statement referencing a 1949 U.N. agreement to which Russia is a signatory.

Read more: U.S. calls on Russia to halt forced deportations of Ukrainians, citing war crimes

Blinken said the U.S. suspects that between 900,000 and 1.6 million Ukrainian citizens, including 260,000 children, have been detained and forcibly deported from their homes to Russia.

— Amanda Macias

Opposition leader Ilya Yashin charged with 'discrediting' the Russian army fighting in Ukraine

Russian opposition figure and Moscow city councilor Ilya Yashin, charged with "discrediting" the Russian army fighting in Ukraine, is escorted inside the Basmanny district court prior to a hearing on his detention in Moscow.

— Getty Images

U.S., allies aim to cap Russian oil prices to hinder invasion

With thousands of sanctions already imposed on Russia to flatten its economy, the U.S. and its allies are working on new measures to starve the Russian war machine while also stopping the price of oil and gasoline from soaring to levels that could crush the global economy.

The Kremlin's main pillar of financial revenue — oil — has kept the Russian economy afloat despite export bans, sanctions and the freezing of central bank assets. America's European allies plan to follow the Biden administration and take steps to stop their use of Russian oil by the end of this year, a move that some economists say could cause the supply of oil worldwide to drop and push prices as high as $200 a barrel.

That risk has the U.S. and its allies seeking to establish a buyer's cartel to control the price of Russian oil. Group of Seven leaders have tentatively agreed to back a cap on the price of Russian oil. Simply speaking, participating countries would agree to purchase the oil at lower-than-market price.

High energy costs are already straining economies and threatening fissures among the countries opposing Russian President Vladimir Putin for the invasion of Ukraine in February. President Joe Biden has seen his public approval slip to levels that hurt Democrats' chances in the midterm elections, while leaders in the United Kingdom, Germany and Italy are coping with the economic devastation caused by trying to move away from Russian natural gas and petroleum.

— Associated Press

Hopes rise that grain exports from Ukraine could resume as talks begin

Ukraine's foreign minister has expressed optimism that a deal to secure grain exports from Ukraine is within reach as a meeting gets underway to break an impasse over the exports, contributing to global food price rises.

"We are two steps away from a deal with Russia. We are in the final phase and now everything depends on Russia," Foreign Minister Dmytro Kuleba told Spanish newspaper El Pais ahead of four-way talks between Ukraine, Russia, Turkey and UN officials that have begun in Istanbul.

More than 20 million tonnes of Ukrainian grain are stuck in silos at the Black Sea port of Odesa, according to Reuters estimates, and many cargo ships have been stranded due to Russia's blockade.

Russia has in turn blamed Ukraine for the stoppage of exports, accusing Kyiv of mining the Black Sea. Both Russia and Ukraine are major wheat exporters, as well as other vital products such as fertilizer and sunflower oil, respectively.

— Holly Ellyatt

Death toll rises to 47 after apartment block missile strike

The death toll from a Russian missile strike on an apartment building in the town of Chasiv Yar in Donetsk in eastern Ukraine has risen to 47.

Kyrylo Tymoshenko, deputy head of the Ukrainian President's Office, said in a Telegram post earlier today that another body of a woman had been recovered from the rubble of the apartment block that was struck on Saturday.

"In total, since the beginning of rescue works, the bodies of 47 dead people, including a child, have been found and removed from the scene. Nine people have been rescued from the rubble. Rescue works are underway," Tymoshenko said.

Russian forces hit the five-storey apartment building in Chasiv Yar. Ukraine has said that the destruction was caused by Russian Uragan rockets. Russia has repeatedly denied targeting civilian targets despite a large number of instances in which civilian infrastructure was targeted, causing death and more displacement for ordinary Ukrainians.

— Holly Ellyatt

Ukraine says it has repulsed attack near Sloviansk, a key Russian target

Ukraine says it has successfully repulsed a Russian assault toward the settlements of Dovhenke and Dolyna, near the city of Sloviansk, a key target for Russian forces trying to advance in the Donetsk region of eastern Ukraine.

The general staff of Ukraine's armed forces said on Wednesday that Russian forces were shelling Ukraine's second-largest city of Kharkiv and surrounding settlements, and also reported non-stop artillery shelling of areas around Sloviansk further south in Donetsk.

"Ukrainian defenders successfully repulsed an assault in the direction of Dovhenke and Dolyna. It is not excluded that the enemy will continue to conduct offensive operations to improve their tactical position and create favorable conditions for conducting an offensive towards Izium - Sloviansk," general staff spokesman Oleksandr Shtupun said in the armed forces' latest update on Facebook.

Widespread shelling was also taking place in the areas around nearby city Kramatorsk and Bakhmut, Ukraine said.

Ahead of a meeting in Istanbul between Ukraine, Russia, the UN and Turkey on unblocking grain exports from Ukraine, the armed forces said that in both the Black Sea and Sea of Azov, Russia's navy "focuses its main efforts on blocking civilian shipping. Four warships armed with Kalibr cruise missiles are kept ready for missile strikes."

Ukraine's armed forces added that the "morale and psychological state of the personnel of the occupiers remains low, systematic consumption of alcoholic beverages and desertion are noted. The occupiers complain about the ineffectiveness of their attacks on Ukrainian positions."

CNBC was unable to verify the information in the report.

— Holly Ellyatt

Russian advances to continue this week as anti-Russian sentiment grows, UK says

In the Donbas, Russian forces will likely focus on taking several small towns during the coming week, Britain's Ministry of Defense said on Wednesday. Siversk and Dolyna are likely to be targets for Russian forces as they approach their bigger objective — the capture of cities Sloviansk and Kramatorsk.

"Russia continues to seek to undermine the legitimacy of the Ukrainian state and consolidate its own governance and administrative control over occupied parts of Ukraine," the ministry said on Twitter.

"Recently this has included an initiative to twin Russian and Ukrainian cities and regions to develop post-conflict administrations and a decree to make it easier for Ukrainians to obtain Russian citizenship."

There is, however, a backlash in Ukraine, the ministry said, with anti-Russian sentiment in occupied parts leading to Russian and pro-Russian officials being targeted. The Russian-appointed administration in Velykyy Burluk acknowledged that one of its mayors was killed on July 11 by a car bombing.

"The targeting of officials is likely to escalate, exacerbating the already significant challenges facing the Russian occupiers and potentially increasing the pressure on already reduced military and security formations," the U.K. said.

— Holly Ellyatt

A 'really difficult road lies ahead,' Zelenskyy says

Ukraine's President Volodymyr Zelenskyy has warned there is a "really difficult road" ahead for his country as Russian forces continue to make small, incremental advances in eastern Ukraine.

In a Telegram post Tuesday evening, Zelenskyy said "a really difficult road is ahead. Everyone understands that. But it is also clear that what lies ahead is the success of our state."

"When millions of people work sincerely for this - each and everyone at their own level - the result will be inevitable," he added.

Zelenskyy's comments come as Russian forces make slow but steady progress in occupying the Donbas region of eastern Ukraine. Russian forces have already seized the Luhansk region of the Donbas and are now advancing into neighboring Donetsk.

Images published on Tuesday showed Russian soldiers patrolling areas of Severodonetsk, a major city in Luhansk and one of the last Ukrainian-held places to fall to Russia in the last few weeks.

 — Holly Ellyatt

Ukrainian ministry says ships are passing through newly opened Danube rivermouth

Ukraine's infrastructure ministry said in a statement that 16 ships had passed through the Danube's newly-reopened Bystre rivermouth in the last four days and that the opening up of the Bystre was an important step towards speeding up grain exports.

— Reuters

Ukraine, U.N., Russia and Turkey to discuss sea corridors for grain exports

The Ukrainian Ministry of Foreign Affairs said it would participate in a four-party meeting with the United Nations, Turkey and Russia on efforts to restart Ukrainian grain exports.

The meeting is slated for Wednesday in Istanbul.

Andriy Yermak from Ukrainian President Volodymyr Zelenskyy's office said on his Telegram channel that the parties will discuss sea corridors for the export of grain, along with security issues.

For months, Russian war ships have blocked Ukrainian ports on the Sea of Azov and the Black Sea.

— Amanda Macias

Death toll from Russian attack on apartment block rises to 41

The death toll from a Russian rocket attack that hit a five-story apartment block in the town of Chasiv Yar in the eastern Ukraine region of Donetsk has risen to 41, according to Ukraine's emergency service.

Search and rescue teams were racing to reach survivors trapped in the rubble after the residential building was struck by Russian rockets over the weekend.

The service said that nine people had been rescued from the rubble as of Monday night.

"Work in progress," Ukraine's emergency services said in a Facebook post as search and rescue teams continued to look for survivors.

— Amanda Macias

Ukraine claims missile attack on Russian ammo depot near occupied Kherson

Ukraine's military says it carried out a missile strike on an ammunition depot near the Russian-occupied port city of Kherson in southern Ukraine.

The strike hit a depot in Russian-held Nova Kakhovka, roughly 35 miles east of Kherson. Ukrainian officials had previously talked about launching counteroffensives to retake land that Russia has occupied since its invasion began in late February.

Moscow denies the Ukrainians hit an ammunition depot, saying it was a fertilizer storage facility that was struck and blown up. Russia also said that the strike damaged houses, a hospital and a market, causing deaths. The information has not been independently verified.

The Associated Press reported significant damage from the blast, seen in satellite imagery, and said in its analysis that the precision of the strike suggested it was carried out with U.S.-supplied High Mobility Artillery Rocket Systems, or HIMARS.

— Natasha Turak

Read CNBC's previous live blog here:

Meeting set to discuss Ukrainian grain exports; Iran set to supply Russia with drones, U.S. says