As the conflict enters its fourth week, Russia and Ukraine are set to resume peace talks on Thursday, according to Kremlin spokesman Dmitry Peskov.

More than 3 million Ukrainians have fled their country and thousands have died, the UN said on Tuesday.

Around 14,000 personnel from the Russian armed forces have been killed so far in the ongoing conflict, the Ukrainian Foreign Ministry said on Thursday. However, the toll could not be immediately verified and Russia has not published casualty numbers since early March.

Zelenskyy makes video speech to U.S. Congress

Ukrainian President Volodymyr Zelenskyy on Wednesday called for a humanitarian no-fly zone over Ukraine when addressing the U.S. Congress.

"This is a terror that Europe has not seen, has not seen for 80 years and we are asking for a reply, for an answer to this terror from the whole world," said Zelenskyy, who during his speech played a video showing damaged buildings and wounded and dead civilians in Ukraine.

"Is this a lot to ask for, to create a no-fly zone over Ukraine to save people? Is this too much to ask?" he said.

He also called for aircraft and anti-aircraft weapons from the U.S.

After Zelenskyy's address, President Joe Biden said that the U.S. would send an additional $800 million in military help to Ukraine. 

Besides, the U.S. would send 100 Sitchblade kamikaze drones to Ukraine as part of the new weapon package, Ukrainian and U.S. media reported.

Russia says 'military operation' not aimed at destroying Ukraine

Losses are mounting in the northern Ukrainian city of Chernihiv, with 53 people killed by Russian forces on Wednesday alone, the regional governor said on Thursday while Russia denies targeting civilians.

Ukrainian Foreign Ministry claimed that Russian forces had dropped a powerful bomb on a theater in the encircled Ukrainian port city of Mariupol where hundreds of civilians were sheltering on Wednesday.

The ministry said many people were trapped in the theater and accused Russia of committing a war crime. It said the number of casualties was not yet known.

In response, Russian Defense Ministry said its forces had not struck the building and instead accused the Azov Battalion, a Ukrainian militia, of blowing it up, RIA news agency said.

At a press conference in Moscow on Thursday, Russian Foreign Ministry spokeswoman Maria Zakharova said the aim of the "special operation" in Ukraine is not to destroy the country's statehood or overthrow the president. She said Russia withdrew from the Council of Europe on its own initiative and, as of March 16, does not consider itself connected with the legal acts of the organization.

Peace talks between two sides set to resume

Touching on the ongoing peace talks between Russia and Ukraine, Kremlin spokesman Dmitry Peskov said on Thursday that "the delegations from Russia and Ukraine will continue negotiations today."

"The fact that negotiations are underway is an indicator of progress," Zakharova said, but she also warned that weapons from the U.S. to Ukraine will become a destabilizing factor and may have dangerous consequences.

Citing Ukrainian Presidential Advisor Mykhailo Podolyak, the Ukraine government-run Ukrinform news agency reported on Wednesday that Zelenskyy may hold talks with his Russian counterpart Vladimir Putin "in the coming days."

(With input from agencies)