This was CNBC's live blog tracking developments on the war in Ukraine on Jan. 4, 2023. See here for the latest updates. 

Russia has been left reeling as the death toll rises following a Ukrainian strike on one of its military units in Makiivka, a city in the partially Russian-occupied Donetsk region in eastern Ukraine.

Russia's Defense Ministry said Tuesday night that the number of servicemen who died in the attack, which took place on New Year's Eve, had risen to 89. Ukrainian and other sources say the actual death toll is much higher.

Russia blamed the unauthorized use of cellphones for the attack, saying that had allowed Ukraine to locate and strike its personnel, though this explanation has also been questioned.

Ukraine has seen no reprieve from the war to start 2023. Russia has hit the country with relentless strikes since New Year's Eve in what President Volodymyr Zelenskyy called Moscow's attempt to "exhaust" his country with prolonged offensives.

Ukraine's president said Tuesday night that his country is prepared for new Russian offensives, saying Moscow would "throw everything they have left" at the war.

Australia says it's buying HIMARS missile systems

Australia announced Thursday it will boost its defense capabilities by spending more than 1 billion Australian dollars ($700 million) on new advanced missile and rocket systems, including U.S.-made HIMARS which have been successfully used by Ukraine's military.

In Ukraine, the mobile, truck-mounted HIMARS have proved crucial in enabling Ukrainian forces to hit key targets, including a recent strike on a single building that killed at least 89 Russian soldiers.

The Australian government said the HIMARS it was buying included launchers, missiles and training rockets and would be in use by 2026. It said the system had a current range of 300 kilometers (186 miles), which was expected to increase with technological advances.

The government said it had also signed a contract with Norway-based Kongsberg to buy Naval Strike Missiles for navy destroyers and frigates, which would replace aging Harpoon anti-ship missiles from next year.

Australia and the U.S. in recent years have become increasingly concerned about China's growing assertiveness in the Pacific.

— Associated Press

Serbian president rejects calls for sanctions against Russia

Serbia's president said that the European Union's calls for his country to join sanctions against Russia over the war in Ukraine represent "a brutal" interference in the internal affairs of the Balkan state, which has asked to join the EU.

In his wide-ranging year-end address to the nation, Aleksandar Vucic praised his and his country's economic and political achievements, comparing himself to a wolf who cannot be tamed under international pressure.

"Thank you very much for meddling in our internal affairs in such a brutal way," he said, referring to the Western appeals.

Although formally seeking EU membership, Serbia has repeatedly ignored calls to align its foreign policies with the 27-nation bloc, including joining international sanctions against Moscow over the war in Ukraine.

There are increasing suggestions from EU-member states that Serbia's membership bid should be suspended until it complies with the bloc's foreign policies.

— Associated Press

Biden says Bradley Fighting Vehicles are on the table for Ukraine

U.S. President Joe Biden said that sending Bradley Fighting Vehicles to Ukraine was being considered to help the Ukrainians in combating Russia's invasion.

"Yes," Biden said when asked if the option was on the table.

— Reuters

Claims that war pits Russia against NATO are 'a bunch of BS,' White House spokesman says

Russian claims that Moscow's war in Ukraine is really a fight against NATO and Western countries are "a bunch of BS," a Biden administration spokesman said.

"This is about a Russian invasion of Ukraine," said U.S. National Security Council spokesman John Kirby. "And Russia is the one who started it. Russia is the one who's visited violence on the Ukrainian people at a scale."

Kirby added that the U.S. will "continue to provide [Ukraine] the kinds of systems and assistance they need to defend themselves," including the coveted High Mobility Artillery Rocket System.

— Jacob Pramuk

Heavy fighting likely to persist in Ukrainian-held Bakhmut, U.S. official says

Heavy fighting around the largely ruined, Ukrainian-held city of Bakhmut is likely to persist for the foreseeable future, with the outcome uncertain as Russians have made incremental progress, according to a senior U.S. administration official.

— Reuters

Russian torture chambers uncovered in Kherson, Ukraine

Kherson police said local residents were held in cells and rooms for days, tortured with electricity and batons and forced to write Russian patriotic texts. Kherson was the only regional capital captured by Russia since the invasion, and Ukraine liberated it late last year.

— Pierre Crom | Getty Images

Zelenskyy and Macron discussed aid to boost Ukraine's air defenses

Ukrainian President Volodymyr Zelenskyy and French President Emmanuel Macron had a "long and detailed conversation" about efforts to boost Ukraine's defenses against Russian attacks.

"We agreed on further cooperation to significantly strengthen our air defense and other defense capabilities," Zelenskyy said in a post on his Telegram channel.

France and other European nations have funneled aid to Ukraine since Russia invaded its neighbor last year. Zelenskyy has pleaded for air defenses in particular as Russia pummels his country with missile strikes.

— Jacob Pramuk

Russia-appointed official says 5 people died in Ukrainian strike on occupied city

The Russian-appointed governor of the Zaporizhzhia region in Ukraine said a Ukrainian strike on the Russian-occupied city of Vasilyevka left five people dead and 15 injured, according to an NBC News translation.

— Jacob Pramuk

Czech government OKs bill for 2% GDP spending on military

The Czech government approved a bill aimed at bringing defense spending at the required NATO goal of 2% of gross domestic product as Russia's war in Ukraine continues.

Defense Minister Jana Cernochova said the move would "ensure a stable and transparent financing of big defense strategic projects in the future."

Cernochova said the war in Ukraine "made it clear we have to be ready for the current and future conflicts and that's why a fast modernization of the army is absolutely necessary."

Although the Czechs will spend only 1.52% of GDP on defense this year, the 2% target should be reached in 2024 once the bill is approved in parliament where the governing coalition has a majority in both chambers.

NATO members agreed in 2014 to commit to the 2% spending target by 2024. Currently, only nine of the Western military alliance's 30 members meet or surpass that goal.

— Associated Press

Ukraine sees speeding up inspections as key to Black Sea grain deal

Ukraine's efforts to increase exports under the Black Sea grain deal with Russia are currently focused on securing faster inspections of ships rather than including more ports in the initiative, a senior Ukrainian official said.

Ukraine is a major global grain producer and exporter, but production and exports have fallen since Russia invaded the country last February and started blockading its seaports.

Three leading Ukrainian Black Sea ports in the Odesa region were unblocked in July under an initiative between Moscow and Kyiv brokered by the United Nations and Turkey. Under the deal, all ships are inspected by joint teams in the Bosphorus.

Kyiv accuses Russia of carrying out the inspections too slowly, causing weeks of delays for ships and reducing the supply of Ukrainian grain to foreign markets. Russia has denied slowing down the process.

— Reuters

Putin sends new hypersonic cruise missiles to Atlantic

Russian President Vladimir Putin on Wednesday sent off a frigate towards the Altantic and Indian oceans armed with new hypersonic Zircon cruise missiles which he said were unique in the world.

In a video conference with Defence Minister Sergei Shoigu and Igor Krokhmal, commander of the frigate named "Admiral of the Fleet of the Soviet Union Gorshkov," Putin said the ship was armed with Zircon hypersonic weapons.

"This time the ship is equipped with the latest hypersonic missile system — 'Zircon' — which has no analogues," said Putin, who is engaged in a standoff with the West over his war in Ukraine.

"I would like to wish the crew of the ship success in their service for the good of the Motherland."

Shoigu said the Gorshkov would sail to the Atlantic and Indian oceans and to the Mediterranean Sea.

"This ship, armed with 'Zircons', is capable of delivering pinpoint and powerful strikes against the enemy at sea and on land," Shoigu said.

Shoigu said the hypersonic missiles, known as either Tsirkon or Zircon, could overcome any missile defense system. The missiles fly at nine times the speed of sound and have a range of over 1,000km, Shoigu said.

Russia, China and the United States are currently in a hypersonic weapons race. Because of their speeds — above five times the speed of sound — and manoeuvrability, such weapons are seen as a way to gain an edge over any adversary.

The target of a hypersonic weapon is much more difficult to calculate than for intercontinential ballistic missiles.

— Reuters

Mariupol sea port being turned into military base, advisor claims

The port of Mariupol is gradually being turned into a military base, an advisor to the occupied city's mayor claimed.

"The occupiers are gradually turning it into a military base," Petro Andriushchenko said on Telegram.

"At the end of December, all residents of Mariupol were released from the port (with the exception of certain specialists-collaborators) and workers were brought in from Moscow. Work has begun on the division of berths into conventionally civilian and conventionally military ones," he said.

Andriushchenko said the port had seen isolated, irregular arrivals of ships carrying building materials and containers of unknown content. He also noted that some port workers had been moved to Crimea in December and that contact with them had then been lost and their whereabouts were unknown to relatives. CNBC was unable to verify the claims.

Mariupol was fully occupied by Russian forces last May following a prolonged siege with Ukrainian fighters holed up in the city's Azovstal steelworks. Russia's relentless bombardment of the city up to its capture left much of it in ruins.

— Holly Ellyatt

Russian army trying to advance through its own corpses in Bakhmut, army chief says

The head of Ukraine's armed forces said fighting in the Luhansk and Donetsk areas around Bakhmut remains intense and difficult.

"Heavy fighting" is taking place between Svatove and Kreminna in Luhansk, as well as toward Lysychansk, the Commander-in-Chief of the Armed Forces of Ukraine Valeriy Zaluzhny said on Telegram Tuesday.

He said the most difficult situation remains in the area of Soledar, Bakhmut and Mayorsk, where "the Russian army is actually trying to move forward through its corpses, but units of the Defense Forces are holding back the advance," Zaluzhny said on Telegram, according to a Google translation of his comments.

Bakhmut has been the epicenter of attritional warfare for several months, with Russian forces gaining little ground in their bid to capture the town, which analysts say has little overall strategic value for Russia.

Despite that, Russia continues to expend weaponry and manpower on its offensive operation in the pocket of Donetsk that is part of the wider Donbas region of eastern Ukraine, which Moscow says it wants to "liberate."

Zaluzhny said Ukraine continued to hold positions around Avdiivka in the Donetsk region and was continuing counteroffensive actions. 

"We are reliably holding defensive lines in the Zaporozhzhia direction and are making efforts to protect Kherson from enemy shelling," he said. The situation on the border with Russia's ally Belarus is fully under control, he added.

— Holly Ellyatt

Infrastructure, apartments and kindergarten damaged in Zaporizhzhia attack, officials say

A missile attack on the city of Zaporizhzhia in southern Ukraine has targeted an infrastructure facility, destroying nearby warehouses and damaging apartment buildings, according to Ukrainian officials.

Kyrylo Tymoshenko, deputy head of the Office of the President of Ukraine, said on Telegram Wednesday that one person had been injured in the rocket attack on the city. He said Russian forces had used S-300 missiles, according to a Google translation of his comments. Tymoshenko's post contained images and video footage purportedly showing the destruction following the attack.

Anatoliy Kurtev, the acting mayor of Zaporizhzhia, urged residents of the city to take shelter, saying on Telegram earlier today that Russian forces were "on the defensive" in the Zaporizhzhia area. He said eight high-rise buildings had been damaged during the attack.

"According to preliminary information, 8 high-rise buildings were damaged in one of the districts of the city ... Their windows were blown out and their balconies were destroyed. In addition, the kindergarten building was damaged. There, too, the windows were broken and the roof was partially damaged," he said on Telegram.

Further information about the attack is still being established, the officials said. CNBC was unable to immediately verify the reports.

— Holly Ellyatt

Ammunition likely being stored near Makiivka troop accommodation, UK says

Britain's Ministry of Defense said on Wednesday it's likely that ammunition is being stored near a Russian military complex that was destroyed in a Ukrainian attack on New Year's Eve, highlighting unsafe and unprofessional practices by the Russian army.

Russia's Defense Ministry said 89 Russian servicemen had died in the attack on the building that was being used as a college and temporary accommodation for newly conscripted soldiers. It's a rare admission of multiple losses by Russia, which blamed the attack on personnel using mobile phones, saying this had enabled Ukraine to target the location.

Britain's Ministry of Defense remarked on Twitter that Ukraine had completely destroyed a school building in Makiivka in Donetsk "which Russia had almost certainly taken over for military use."

"Given the extent of the damage, there is a realistic possibility that ammunition was being stored near to troop accommodation, which detonated during the strike creating secondary explosions."

It noted that the building was only 7.7 miles from the Avdiivka section of front line, "one of the most intensely contested areas of the conflict."

"The Russian military has a record of unsafe ammunition storage from well before the current war, but this incident highlights how unprofessional practices contribute to Russia's high casualty rate," U.K.'s defense ministry added.

— Holly Ellyatt

Russia ready to 'throw everything they have left' at the war, Zelenskyy says

Ukraine's President Volodymyr Zelenskyy said Tuesday night that Kyiv is prepared for renewed offensives and mobilization by Russia.

Zelenskyy said on Telegram that he had spoken with his counterparts in Canada, the Netherlands, U.K. and Norway on Tuesday, with the conversation focusing on "what Ukraine immediately needs most right now — on the eve of those new mobilization processes being prepared by the terrorist state."

"Right now is the moment when, together with our partners, we should strengthen our defense. We have no doubt that the present masters of Russia will throw everything they have left, and all they can muster, into trying to turn the tide of the war, and at least delay their defeat. We have to disrupt this Russian scenario. We are preparing for it," Zelenskyy said, adding that "any attempt at their new offensive must fail."

— Holly Ellyatt

Russia blames use of mobile phones for deadly Makiivka attack

Russia has been left reeling as the death toll rises following a Ukrainian strike on newly conscripted soldiers in Makiivka, a town in the partially Russian-occupied eastern Donetsk region in east Ukraine.

Russia's Defense Ministry said Tuesday night that the death toll from the attack, which took place on New Year's Eve, had risen to 89, according to reports by Russian state news agencies.

It had previously said 63 soldiers had died in the attack, which struck a college for conscripts in Makiivka, in a rare admission of multiple losses.

It blamed the unauthorized use of cellphones for the strike, saying their use had allowed Ukraine to locate and strike its personnel.

"This factor allowed the enemy to locate and determine the coordinates of the location of military personnel for a missile strike," the ministry said in a statement, reported by RIA Novosti.

The ministry said Ukraine had struck the building in Makiivka using missiles from a HIMARS rocket system and claimed that Russian forces had intercepted four of six rockets. It claimed it had destroyed the HIMARS rocket system from which the attack was carried out. CNBC was unable to verify the defense ministry's claims.

The attack has caused consternation in Russia, with mourners gathering in Samara, the region where the majority of the mobilized soldiers reportedly came from.

— Holly Ellyatt

Moscow’s invasion is likely to inflict long-term economic decline on Russia

Moscow thought it would emerge from the Ukraine invasion with a bigger role on the global stage. But it's growing more isolated and looks likely to face a long-term economic decline. CNBC's Ted Kemp reports.

Russians angry at commanders over Ukrainian strike that killed scores

Russian nationalists and some lawmakers have demanded punishment for commanders they accused of ignoring dangers as anger grew over the killing of dozens of Russian soldiers in one of the deadliest strikes of the Ukraine conflict.

In a rare disclosure, Russia's defense ministry said 63 soldiers were killed in the Ukrainian strike on New Year's Eve that destroyed a temporary barracks in a vocational college in Makiivka, twin city of the Russian-occupied regional capital of Donetsk in eastern Ukraine.

Russian critics said the soldiers were being housed alongside an ammunition dump at the site, which the Russian defense ministry said was hit by four rockets fired from U.S.-made HIMARS launchers.

TV footage showed a huge building reduced to rubble as cranes and bulldozers picked through concrete debris lying several feet deep.

Ukraine and some Russian nationalist bloggers put the Makiivka death toll in the hundreds, though pro-Russian officials say those estimates are exaggerated.

Rallies to commemorate the dead were held in several Russian cities, including Samara, where some came from, RIA Novosti news agency reported. Mourners laid flowers in the center of Samara.

"I haven't slept for three days, Samara hasn't slept. We are constantly in touch with the wives of our guys. It's very hard and scary. But we can't be broken. Grief unites ... We will not forgive, and, definitely, victory will be ours," RIA quoted Yekaterina Kolotovkina, a representative of a women's council at an army unit, as telling one of the rallies.

— Reuters

Russia, shaken by Ukrainian strike, could step up drone use

Emergency crews sifted through the rubble of a building struck by Ukrainian rockets, killing at least 63 Russian soldiers barracked there, in the latest blow to the Kremlin's war strategy as Ukraine says Moscow's tactics could be shifting.

An Associated Press video of the scene in Makiivka, a town in the partially Russian-occupied eastern Donetsk region, showed five cranes and emergency workers removing big chunks of concrete under a clear blue sky.

In the attack, which apparently happened last weekend, Ukrainian forces fired rockets from a U.S.-provided HIMARS multiple launch system, according to a Russian Defense Ministry statement.

It was one of the deadliest attacks on the Kremlin's forces since the war began more than 10 months ago and an embarrassment that stirred renewed criticism inside Russia of the way the war is being conducted.

The Russian statement Monday about the attack provided few other details. Other, unconfirmed reports put the death toll much higher.

The Strategic Communications Directorate of Ukraine's armed forces claimed Sunday that around 400 mobilized Russian soldiers were killed in a vocational school building in Makiivka and about 300 more were wounded. That claim couldn't be independently verified. The Russian statement said the strike occurred "in the area of Makiivka" and didn't mention the vocational school.

— Reuters

Russia aims to 'exhaust' Ukraine with continued attacks, Zelenskyy says

Russia aims to "exhaust" Ukraine with a prolonged stream of attacks across the country, Ukrainian President Volodymyr Zelenskyy said in his nightly address.

"We must ensure - and we will do everything for this - that this goal of terrorists fails like all the others," he said. "Now is the time when everyone involved in the protection of the sky should be especially attentive."

Russian strikes on Ukrainian cities and infrastructure have ramped up of late, marking three consecutive nights of bombardment in the latest stream of attacks that began on New Year's Eve. The strikes target Ukraine's energy facilities in particular, leaving millions of people without heating and power amid the bitter winter cold.

Russian forces are increasingly leaning on deadly Iranian-made Shahed drones, which have wrought havoc on Ukraine's cities. Zelenskyy said that Ukrainian air defenses shot down more than 80 of such drones in the first days of January.

— Natasha Turak

Read CNBC's previous live coverage here:

Russians are angry over deadly Ukrainian strike; Zelenskyy says Moscow aims to 'exhaust' Ukraine with attacks