At least two people were killed and 19 others injured from a Russian drone attack in northern Ukraine, the Sumy Regional Military Administration said.

An administrative building and two apartment buildings were damaged in the four drone strikes, officials said.

Four people have been hospitalized, according to officials. Two of the patients were listed in intensive care.

Ukrainian President Volodymyr Zelenskyy said in his daily evening address that the lack of air defense systems is part of the reason buildings were hit.

"The enemy is taking advantage of this," he said.

-ABC News' Ellie Kaufman

Lynne Tracy, the U.S. ambassador to Moscow, met with detained American journalist Evan Gershkovich on Monday, the ambassador's press secretary told ABC News.

Tracy met with Wall Street Journal reporter at Moscow's Lefortovo prison where he's being held, according to the press secretary.

This is the second visit between Tracy and Gershkovich since his initial detention in March.

-ABC News' Tanya Stukalova and Ellie Kaufman

Yevgeny Prigozhin, the Wagner Group leader who led the rebellion in Russia, reportedly released a new message Monday, his first in a week, to a social media account with ties to the PMC.

In a short audio message posted by Grey Zone telegram account, which believed to be run by a Wagner member that frequently posts about events on the frontline in Ukraine, Prigozhin claimed the June 24 rebellion against Moscow was aimed at "fighting traitors and mobilizing our society."

"I think we have achieved a lot of it. In the near future, I am sure that you will see our next victories at the front. Thanks guys," he allegedly said.

The Wagner Group leader said "today, more an ever, we need your support."

-ABC News' Patrick Reevell

Amid fears Russia might blow up the Zaporizhzhia nuclear power plant, Ukraine is holding drills to prepare emergency services with how to deal with a potential radioactive disaster.

ABC News was invited to the drills in the city of Zaporizhzhia this week, about 30 miles from the plant, where firefighters in hazmat gear simulated decontaminating people from radiation during an evacuation.

Emergency workers demonstrated scanning civilians with Geiger counters as they disembarked buses, stripping some civilians and hosing them with water as they lay on stretchers. Firefighters in yellow suits sprayed down vehicles and moved them through a large washer system rigged up between fire trucks.

This week, Ukraine's chief of military intelligence, Kyrylo Budanov, claimed Russia had now completed preparation to potentially sabotage the plant if it chooses.

Read more about the drills here.

-ABC News' Patrick Reevell

U.S. President Joe Biden and other G-7 leaders are set to unveil future support for Ukraine on Wednesday after the conclusion of a high-stakes NATO summit in Lithuana's capital.

"President Biden and G-7 leaders will make a major announcement alongside President Zelenskyy this afternoon outlining our long-term commitments to support the people of Ukraine," U.S. National Security Council Senior Director for Europe Amanda Sloat said during a press briefing in Vilnius on Wednesday morning. "The United States, along with G-7 leaders, will announce our intent to help Ukraine build a military that can defend itself and deter a future attack."

"The launch of this process today will start a series of bilateral negotiations with Ukraine on the reaching of bilateral security commitments to help make this a reality," she added. "In particular, this process will ensure that the military assistance we provide Ukraine to defend itself against Russian aggression continues to be part of a long-term investment in Ukraine’s future force."

That investment will include making sure "Ukraine has a sustainable fighting force capable of defending Ukraine now and deterring Russian aggression in the future, a strong and stable economy, and the help Ukraine needs to advance the reform agenda to support the good governance necessary to advance Ukraine's Euro-Atlantic aspirations, which Ukraine recommits itself to as part of this declaration," according to Sloan.

"Taken together, we believe the declaration we will announce today seeks to ensure Ukraine's future as a free, independent, democratic, and sovereign nation," she told reporters. "This multilateral declaration will send a significant signal to Russia that time is not on its side."

-ABC News' Molly Nagle