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

The head of the United Nations nuclear watchdog group said Thursday that he is worried the world is becoming complacent about the "very precarious" situation posed by the Russian-controlled Zaporizhzhia nuclear plant in Ukraine.

Russian forces seized the plant, Europe's largest, in March 2022 and it has repeatedly come under fire in recent months, raising fears of a nuclear disaster. Rafael Grossi, director general of the U.N.'s International Atomic Energy Agency (IAEA), is working to set up a safe zone around the facility.

"I think the situation is very precarious," Grossi told reporters in the Ukrainian capital of Kyiv. "I worry that this is becoming routine, that people may believe that nothing has happened so far, so is the director general of the IAEA crying wolf?"

Grossi said two major explosions occurred near the plant on Thursday, adding to the alarming situation.

"We know every day that a nuclear accident or an accident having serious radiological consequences may take place," said Grossi before travelling to Moscow for talks with Russian officials.

Ukrainian President Volodymyr Zelenskyy on Thursday pleaded with leaders of the European Union to pursue new sanctions against Russia's nuclear industry and energy carriers.

During a joint news conference in Kyiv with European Council President Charles Michel, Zelenskyy said he believes a tenth package of sanctions "could be even more effective" than the previous ones.

"The time has come, in particular, for sanctions against the Russian nuclear industry, against all its branches, organizations and all entities that work for the Russian missile program," Zelenskyy said.

He also expressed his frustration over Germany's hesitation to send Leopard tanks Ukraine.

"The issue of tanks remains relevant and very sensitive," Zelenskyy said. "It depends on many reasons and, unfortunately, does not depend on the will of Ukraine. We create pressure as hard as we can politically, but the essential thing is that our pressure is well-reasoned."

Zelenskyy added, "Against thousands of tanks of the Russian Federation, as I told our colleagues, only the courage of our military and the motivation of the Ukrainian people are not enough."

Since the United Kingdom announced last week it will send Challenger 2 tanks to Russia, the German government has faced mounting pressure to follow suit, or at least allow NATO allies such as Poland to supply Ukraine with German-made Leopard tanks.

"The delivery of Leopard tanks to Ukraine is still a matter of dispute in the Bundestag (national parliament)," according to a statement released Thursday by the German government, which added that the issue is still the subject of "heated debate."

A U.S. official confirmed to ABC News that the upcoming aid package to Ukraine will include close to 100 Stryker Armored Vehicles and additional Bradley fighting vehicles.

The Stryker is a wheeled armored vehicle that can carry as many as 11 soldiers inside and is equipped with a 30mm gun and or machine gun that are remotely fired from inside the vehicle. It’s fast moving and can be used on roads or off roads, though the off road option is better handled by the tracked Bradley fighting vehicles.

-ABC News' Luis Martinez

Ukrainian President Volodymyr Zelenskyy provided an update on the helicopter crash near Kyiv near a kindergarten.

Zelenskyy said 14 people were killed in total including Ukrainian Interior Minister Denys Monastyrski and one child.

Twenty-five people were injured, including 11 kids, the president added.

"Hundreds of people were involved in extinguishing the fire, searching and rescuing the injured, carrying out the initial investigative actions," Zelenskyy said.

The president praised the efforts of kindergarten teachers who rushed in to help.

"Thank you for your bold actions, for taking the children out," he said.

Zelenskyy said the Ministry of Internal Affairs will be temporarily led by the head of the National Police of Ukraine.

"The tasks for which the Minister was responsible in the context of our defense operation and ensuring the security of the state have also been distributed," he said.

The cause of the helicopter crash is still under investigation.

-ABC News' Wil Gretsky