Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty

Belarus would only join the war in Ukraine, fighting alongside Russia, if it is attacked, President Alexander Lukashenko told state-run Belta news agency.

"We don't want a war. And in no case are we going to send our troops into the territory of Ukraine. Unless you commit aggression against the territory of Belarus from there. Here is my answer. It was given a long time ago," Lukashenko said.

Ukrainian President Volodymyr Zelenskyy addressed Lukashenko's threat in an interview with the BBC.

"I hope [Belarus] won't join [the war]," he said. "If it does, we will fight and we will survive."

Allowing Russia to use Belarus as a staging post for an attack again would be a "huge mistake," he added.

Russian forces launched part of their full-scale invasion from Belarus 12 months ago. They drove south toward Ukraine's capital, Kyiv, but were fought back and made to retreat within weeks, after suffering heavy casualties.

Lukashenko is set to meet with Russian President Vladimir Putin on Friday.

-ABC News' Will Gretsky and Tanya Stukalova

Ukraine's President Volodymyr Zelensky has ruled out giving up any of his country's territory in a potential peace deal with Russia.

In a BBC interview to mark a year since Russia's full-scale invasion, he warned conceding land would mean Russia could "keep coming back," while Western weapons would bring peace closer.

However, he does believe Ukrainian forces can keep resisting Russia's advance until they are able to launch a counteroffensive -- although he repeated his calls for more military aid from the West.

"Of course, modern weapons speed up peace. Weapons are the only language Russia understands," Zelensky told the BBC.

-ABC News' Will Gretsky

An infrastructure object was hit in Lviv in the early morning hours of Thursday, the head of the Lviv Regional Military Administration, Maksym Kozytskyi, said on Telegram.

There were no casualties, and the fire from the impact has since been put out, Kozytskyi said.

Six Kalibr missiles were also shot down over the Mykolaiv region, and two Kalibr missiles were shot down over the Kherson region overnight, Odesa Military Administration spokesman Serhii Bratchuk posted on Telegram.

All eight of the missiles were fired from a Russian ship in the Black Sea, Bratchuk said in the post.

-ABC News' Ellie Kaufman

Authorities in Kyiv are investigating who owns six balloons that were in Ukraine's airspace and what the balloons were doing over Kyiv. The balloons were shot down by Ukrainian air defense.

After a preliminary assessment, authorities think the balloons had intelligence gathering equipment.

-ABC News' Will Gretsky