"Difficult" negotiations are underway between Ukraine and Russia to coordinate the evacuation of seriously wounded fighters from the Azovstal steel plant in Mariupol in exchange for an unspecified number of Russian prisoners of war, Ukrainian Deputy Prime Minister Iryna Vereshchuk said.

"We are currently negotiating only 38 severely wounded fighters that can't walk," she said.

-ABC News' Irene Hnatiuk

Russia "will be forced to take retaliatory steps both of military-technical and of other nature in order to stop the threats to its national security" in response to Finland’s possible accession to NATO, according to state-run TASS citing a statement by the Russian Foreign Ministry.

The ministry added, "Finland joining NATO will seriously harm bilateral Russian-Finnish relations and the maintenance of stability and security in the North European region."

Russia will conduct a "special analysis" and take necessary measures for national security if Finland joins NATO, Kremlin spokesman Dmitry Peskov said Thursday.

"There is an order from the president, the supreme commander-in-chief, that a list of measures be composed to strengthen our western flanks in connection with the strengthening of the eastern flank of NATO," Peskov told reporters during a daily briefing. "NATO has been enlarging towards us. So, clearly, all of that will be elements of a special analysis and the elaboration of measures necessary for maintaining a balance and providing our security."

"Everything will depend on the manifestation of the further [NATO] enlargement process -- how far the military infrastructure will grow towards our borders," he added.

When asked whether Finland's accession to NATO -- the world's biggest military alliance -- would pose a threat to Russia, Peskov told reporters: "Of course it will."

"Another enlargement of NATO does not make our continent more stable and secure," he said.

Peskov's comments followed a joint statement released by Finnish President Sauli Niinisto and Finnish Prime Minister Sanna Marin announcing their support for Finland applying to join NATO.

Finland's leaders announced Thursday their support for the country applying to join NATO, the world's biggest military alliance.

"During this spring, an important discussion on Finland's possible NATO membership has taken place. Time has been needed to let Parliament and the whole society establish their stands on the matter," Finnish President Sauli Niinisto and Finnish Prime Minister Sanna Marin said in a joint statement. "Time has been needed for close international contacts with NATO and its member countries, as well as with Sweden. We have wanted to give the discussion the space it required."

"Now that the moment of decision-making is near, we state our equal views, also for information to the parliamentary groups and parties. NATO membership would strengthen Finland's security," they added. "As a member of NATO, Finland would strengthen the entire defence alliance. Finland must apply for NATO membership without delay. We hope that the national steps still needed to make this decision will be taken rapidly within the next few days."

The Finnish Parliament will now take up the issue, with a vote expected to be held early next week.

The announcement marks a major shift in Finland's traditionally neutral policy, triggered by Russia's ongoing invasion of Ukraine. Finland shares an 830-mile border with Russia, and recent opinion polls show Finnish public support for joining NATO has surged to 76%.

Neighboring Sweden is also considering applying to join the alliance.

-ABC News' Ines de la Cuetara

At least one person -- a journalist -- was killed in a rocket attack on a residential building in Kyiv on Thursday evening, ABC News has learned.

Kyiv Mayor Vitali Kilitschko said Friday that rescuers had found the body of a victim amid the rubble.

Radio Liberty, a service of the U.S.-funded Radio Free Europe/Radio Liberty, reported that one of its employees, Vira Gyrych, was killed when a Russian missile hit her apartment in the Ukrainian capital on Thursday. Her body was found beneath the wreckage Friday morning, according to the report.

Gyrych had worked as a journalist and producer for Radio Liberty's Kyiv bureau since 2018. Prior to that, she worked for leading Ukrainian television channels, according to Radio Liberty.

"The editorial staff of Radio Liberty expresses its condolences to the family of Vira Gyrych and will remember her as a bright and kind person, a true professional," Radio Liberty said in its report.

Israeli Ambassador to Ukraine Michael Brodsky also confirmed Gyrych's death in a Twitter post, saying she was a former employee of the Israeli embassy in Kyiv.

Thursday's rocket attack came as United Nations Secretary-General Antonio Guterres visited Kyiv. Five Russian missiles flew into the city, according to Ukrainian President Volodymyr Zelenskyy. At least 10 people were injured, including four who were hospitalized, according to the Kyiv City Council.