This was CNBC's live blog tracking developments on the war in Ukraine.

Russian drone strikes on Kharkiv early Thursday morning killed at least four people, including three rescue workers, and injured 12 more, according to Ukrainian officials.

In a post on the Telegram messaging app, Kharkiv Mayor Igor Terekhov said Iranian-made shahed drones struck a 14-story residential apartment block, destroying several floors and resulting in a death and multiple casualties.

A repeat attack on a separate area of Ukraine's second-largest city killed three rescue workers who had arrived on the scene after the first strike, he added.

As NATO foreign ministers gather in Brussels to mark the defense alliance's 75th anniversary, Kremlin spokesman Dmitry Peskov reportedly said on Thursday that relations between Russia and NATO have "slipped to the level of direct confrontation."

Russian Deputy Foreign Minister Alexander Grushko told state news agency RIA in an interview published Thursday that dialog with Moscow had been reduced to a "critical zero" by Washington and Brussels.

However, Grushko reportedly said that Russia has no intention of entering into open conflict with any NATO member.

Correction: This blog has been updated to reflect that the Russian drone strikes on Kharkiv occurred early Thursday morning.

Russia detains three more people over concert hall attack

Russia has detained three more people suspected of being involved in last month's deadly attack at a concert hall near Moscow, the FSB security service was quoted as saying on Thursday.

A Russian citizen and two foreign nationals, all originally from the Central Asian region, were detained in Moscow, Yekaterinburg and Omsk, news agency RIA Novosti reported via Telegram, citing the FSB.

At least 144 people were killed in a mass shooting and fire at the Crocus City Hall concert venue in late March, an attack that was claimed by the Islamic State militant group .

— Sam Meredith

Russian-installed officials say six civilians killed in Ukrainian attacks

Russian-installed officials said a total of six civilians were killed on Thursday in Ukrainian attacks on Russian-controlled parts of southern and eastern Ukraine.

A Russian official in Kherson region, Andrey Alekseenko, said two people died in a village where one drone struck a car and a second drone was fired at a passenger who had managed to crawl away from the vehicle.

He said a separate attack killed two members of a repair crew that was working to restore mobile communications. Another person was in hospital in critical condition.

Russian-installed officials in Donetsk in eastern Ukraine, said two people had been killed there on Thursday by Ukrainian shelling and nine others were wounded.

Russia and Ukraine deny targeting civilians in the war that is now in its third year. The U.N. Human Rights Monitoring Mission said in February that more than 10,000 civilians had been killed in Ukraine and nearly 20,000 wounded.

— Reuters

France’s Macron says he has ‘no doubt’ Russia will target Paris Olympics

French President Emmanuel Macron said on Thursday he had "no doubt" Russia would seek to disrupt the running of the Paris Olympics this summer.

"I have no doubt, including in informational terms," Macron said when asked whether he was concerned Russia would specifically target the Olympics. His comments came on the sidelines of an event held in Saint-Denis outside Paris for the inauguration of an Olympic aquatics center.

The summer Olympic Games will take place in the French capital from July 26 through to Aug. 11, with the Paralympic Games scheduled for Aug. 28 through to Sept. 8.

"We are preparing these Olympic and Paralympic Games collectively, there is a colossal amount of work being done by the elected officials around me, by their services, by the sporting world, by state services," Marcon said, according to a translation.

The Russian Embassy in London and Russia's Foreign Ministry did not immediately respond to CNBC's request for comment.

— Sam Meredith

In pictures: NATO marks 75th anniversary as foreign ministers meet in Belgium

Photos published by Getty Images on Thursday showed foreign ministers of NATO member states gathered at the military alliance's headquarters in Brussels, Belgium to commemorate the group's 75th anniversary.

— Sam Meredith, Adam Jeffrey

Finland extends Russian border closure indefinitely

Finland has extended the closure of its border with Russia indefinitely, the government announced Thursday.

The new NATO member state closed its 13 points of entry from Russia late last year after accusing the Kremlin of deliberately funnelling undocumented migrants to its eastern border in a bid to sow instability, an allegation Moscow denies.

In February, Finland said the closures would extend until April 14, but Interior Minister Mari Rantanen said in a statement that Helsinki had seen nothing to suggest that the situation had changed meaningfully in recent months.

— Elliot Smith

Russia's Lavrov says Chinese peace plan is most reasonable so far

Russian Foreign Minister Sergei Lavrov on Thursday said China's 12-point peace plan for Ukraine is "reasonable," despite Western criticism, according to Russia's RIA state news agency.

China published the proposals in February last year, but they were widely criticized for being too vague and failing to honor Ukraine's territorial integrity and sovereignty as an independent nation.

"The most important thing for us is that the Chinese document is based on an analysis of the reasons for what is happening and the need to eliminate these root causes. It is structured in logic from the general to the specific," state news agency RIA quoted Lavrov as telling reporters on Thursday.

"This plan was criticized for being vague ... But this is a reasonable plan that the great Chinese civilization proposed for discussion."

— Elliot Smith

Kremlin says NATO relations have 'slipped to the level of direct confrontation': Reports

Kremlin spokesman Dmitry Peskov reportedly said on Thursday that relations between Russia and NATO have "slipped to the level of direct confrontation."

Peskov told reporters on a press call that the transatlantic defense alliance, which is celebrating its 75th birthday this week, was "already involved in the conflict surrounding Ukraine" and continues to expand towards Russia's borders.

NATO's eastward expansion is a long-standing bugbear for Russian President Vladimir Putin, deepened by the recent ascension of Sweden and Finland to the alliance and Ukraine's vocal desire to join.

Peskov's comments come after Russia's Deputy Foreign Minister Alexander Grushko said in an interview with state news agency RIA, published Thursday, that dialog between Moscow and NATO was at a "critical zero," but that Russia has no intention of entering into open conflict with any member state.

- Elliot Smith

NATO 100 billion euro aid package would be 'too little' and 'too late' as Ukraine struggles for ammo, professor says

Michael Clarke, visiting professor in the department of war studies at King's College London, tells CNBC that NATO's potential 100 billion euro ($108.5 billion) aid package for Ukraine, spread out over five years, would be "too little" and "too late" if Ukraine is unable to satisfy its urgent ammo requirements.

Ukraine says 350,000 Kharkiv residents without power after drone strikes

Ukraine's energy ministry said Thursday that 350,000 residents of Kharkiv and the surrounding regions were without electricity after another barrage of Russian drone attacks overnight.

Russia has been attacking Ukrainian energy infrastructure in recent weeks, but the energy ministry said on the Telegram messaging app that the disconnections were part of hourly blackout schedules and that no ongoing shortage of electricity is expected.

It also said no further restrictions are expected in other areas of the country.

- Elliot Smith

France denies readiness to talk with Russia over Ukraine: Reuters

France has denied showing readiness for potential talks with Russia over Ukraine, refuting Moscow's account of a call on Wednesday between French Defense Minister Sebastian Lecornu and his Russian counterpart Sergei Shoigu.

Russia's defense ministry said in a statement that "readiness for a dialog on Ukraine was noted" and that "the starting points could be based on the Istanbul peace initiative."

No such details were present in the French readout, which showed Lecornu and Shoigu discussing the heightened terror threat following the recent mass shooting in Moscow claimed by ISIS-K, an Islamic State affiliate.

Reuters subsequently quoted a French government source as saying the Russian account was "not true" and that no mention was made of future talk over Ukraine.

- Elliot Smith

Russia's Grushko: NATO-Moscow dialog at 'critical zero,' but no intention of open conflict

As NATO foreign ministers gather in Brussels to mark the defense alliance's 75th anniversary, Russian Deputy Foreign Minister Alexander Grushko told state news agency RIA that dialog with Moscow had been reduced to a "critical zero" by Washington and Brussels.

Grushko reportedly said relations were "predictably and deliberately" deteriorating, but that Russia has no intention of entering into open conflict with any NATO member.

— Elliot Smith

Russian drone strike in Kharkiv kills four, including three rescue workers

Russian drone strikes on Kharkiv early Thursday morning killed four people, including three rescue workers, and injured 12 more, according to Ukrainian officials.

In a post on the Telegram messaging app, Kharkiv Mayor Igor Terekhov said Iranian-made shahed drones struck a 14-story residential apartment block, destroying several floors and resulting in a death and multiple casualties.

"Three rescuers died during a repeated attack on a residential building in another place. In total, we have four dead," Terekhov added.

"Also among the victims was an emergency medical nurse who, together with the brigade, arrived at the scene to provide assistance."

— Elliot Smith

Images show the latest from the Russia-Ukraine war

Photos published via Getty Images on Wednesday show people reacting to Russian shelling in the Sumy region of northern Ukraine and a military band performing to commemorate the 34th anniversary of raising the Ukrainian flag in western Lviv.

— Sam Meredith

Russian Prosecutor General’s Office sends Western countries inquiries over terror attacks

The Russian Prosecutor General's Office sent official requests for information to the U.S., France, Germany and Cyprus over its suspicion of Western states' potental involvement in terror attacks inside Russia, state news outlet Tass reported, citing a statement from the government office.

Tass reported that the office was prompted to send the inquiries following requests from members of Russia's State Duma to investigate potential foreign involvement in terror attacks including the attack at Moscow's Crocus City concert hall in late March which killed at least 144 people, as well as the Nord Stream gas pipeline explosions.

In its statement, Russia's top prosecution body said it hoped that "our colleagues in these countries will earnestly consider the requests and fulfill their obligations under the 1999 International Convention for the Suppression of the Financing of Terrorism and the 1997 International Convention for the Suppression of Terrorist Bombings, which involve investigating the information provided, facilitating efforts to obtain evidence necessary for probes, and ensuring that punishments be duly carried out."

— Natasha Turak

NATO's Stoltenberg pitches plan to change how aid is sent to Ukraine

NATO Secretary-General Jens Stoltenberg is pressing for the alliance to be more directly involved in the delivery of military aid to Ukraine.

Speaking at the meeting of NATO foreign ministers in Brussels, Stoltenberg said the organization will examine how it can take on a greater role in coordinating weapons and other equipment for Kyiv — something that has thus far been the purview of a U.S.-led contact group.

"Ukraine has urgent needs — any delay in providing support has consequences on the battlefield as we speak," Stoltenberg told the meeting's attendees. "So we need to shift the dynamics of our support."

"We must ensure reliable and predictable security assistance to Ukraine for long haul so that we rely less on voluntary contributions and more on NATO commitments, less on short term offers and more on multiyear pledges," he said, declining to provide specifics but adding that a multi-year financial commitment would also be part of the plan.

"NATO allies provide 99% of all military support to Ukraine," he said. "So doing more under NATO would make our efforts more efficient and more effective."

— Natasha Turak

Ukraine thanks Finland for 188 million euro military aid package

Ukraine's defense minister thanked Finland for a 188 million euro ($202.5 million) military aid package the Nordic country announced for Kyiv, detailing the two countries' latest cooperation in a post on X.

"I am grateful to our Finnish partners and Minister @anttihakkanen for another military aid package for Ukraine valued at up to €188 million," Rustem Umerov wrote in his post. "We also strengthened our defense cooperation: today, Ukraine and Finland signed an agreement on security cooperation and long-term support."

"Finland will provide long-term military and financial assistance and step up political, financial, humanitarian, and reform cooperation," the post read. "Together, we are stronger. Thank you for your steadfast support."

— Natasha Turak

Read CNBC's previous live coverage here:

NATO chief floats 100 billion euro fund for Kyiv; Ukraine shoots down 4 Russian drones overnight