Russia-Ukraine updates: Russian missiles hit close to nuclear reactors: IAEA director

Russian missiles struck residential areas near the key port city of Odesa in southern Ukraine early Friday, killing at least 21 people and wounding 39 others, Ukrainian authorities said.

Russian bombers fired a trio of X-22 missiles that hit a nine-story apartment building and two recreational areas in the small coastal town of Serhiivka, located about 31 miles southwest of Odesa, according to a statement from the Security Service of Ukraine, which noted that rescue operations were underway.

Many victims were in the apartment building, where the entire entrance was "completely destroyed," authorities said.

One of the wounded children was a baby who was in a coma after being pulled from the charred rubble, according to authorities.

"This was a targeted Russian missile attack -- Russian terror against our cities, villages, our people," Ukrainian President Volodymyr Zelenskyy said.

The pre-dawn attacks followed the withdrawal of Russian forces from Ukraine's Snake Island on Thursday, a move that was expected to potentially ease the threat to nearby Odesa, home to Ukraine's biggest seaport and one of the largest ports in the Black Sea basin.

"Occupants can't win on the battlefield, so resort to the vile murder of civilians," Ivan Bakanov, chairman of the Security Service of Ukraine, said in a statement Friday. "After the enemy was kicked out of Snake Island, he decided to respond with a cynical shelling of civilian objects."

Ukraine on Friday submitted a memorandum to the International Court of Justice on Russian aggression.

"We prove that Russia violated the Genocide Convention by justifying its aggression with a false pretext of a 'genocide' that never was," tweeted Dmytro Kuleba, Ukrainian Minister of Foreign Affairs.

He called it a "critical step to hold Russia accountable and make Russia pay for the harm it has inflicted."

Close to 90% of refugees who fled Ukraine since the start of Russia's invasion plan to return home at some point, according to a recent poll by the Rating group.

Only 8% of refugees said they would never return to Ukraine, while 15% are prepared to go back as soon as possible, the poll showed.

Around half of those displaced only plan on returning when the war is over. Close to a third of people who lost their jobs because of the war are still not able to find new employment, the data revealed.

-ABC News' Edward Szekeres, Max Uzol, Fidel Pavlenko and Yuriy Zaliznyak

Russia has dismissed reports from Ukrainian officials that Russian missiles struck residential areas in the southern town of Odesa early on Friday morning and reiterated its claim that Moscow does not target civilians.

“I would like to remind you of president [Vladimir Putin's] words that the Russian Armed Forces do not engage with civilian targets,” Kremlin spokesman Dmitry Peskov said on a conference call with reporters on Friday.

Ukrainian authorities had earlier said Russian missiles hit an apartment building and two holiday camps in the region, killing at least 20 people and wounding dozens of others, including children.

To counter the threat of indiscriminate Russian strikes, NATO Secretary General Jens Stoltenberg pledged more supplies of advanced weapons and equipment to Ukraine on Thursday.

Speaking at a press conference in Madrid, Stoltenberg said NATO has a list of requested equipment and nothing would be ruled out or excluded from that list. Several NATO countries expressed reservations about the transfer of some weapons –- including tanks and other heavy weapons -– to Ukraine in the first months of the war.

-ABC News' Edward Szekeres, Max Uzol, Fidel Pavlenko and Yuriy Zaliznyak