Ukrainian President Volodymyr Zelenskyy announced Wednesday the Security Service of Ukraine and the police arrested a suspect who they say coordinated with Russian forces in Tuesday's missile attack on Kramatorsk, a city in the Donetsk region.

The missiles struck a popular pizzeria and killed 12 people, including three children. More than 60 people were injured, the president said in a public address.

The unidentified "spotter" was charged with treason, according to Zelenskyy.

"Anyone in the world who does not understand that one cannot be an accomplice of a terrorist state must be held accountable by the entire international community," he said.

-ABC News' Will Gretsky

A senior U.S. official tells ABC News that Yevgeny Prigozhin thought he would have help from the Russian military.

Both former Russian military officers and some others in Moscow had conversations with Prigozhin before he started his march, the official said.

The U.S. doesn't believe Russian President Vladimir Putin realized this beforehand, and the officers sided with Putin in the end, the official said.

According to the official, Prigozhin was shocked he didn’t have support.

-ABC News' Martha Raddatz

Two Russian missiles struck Kramatorsk, a city in Ukraine's Donetsk region, killing at least four people, according to officials.

At least 47 people were injured in the attack, but the death and injury toll could rise.

One of the deceased victims was a 15-year-old and one of the wounded victims was a child under a year-old, officials said.

One missile struck an eatery downtown and the other one hit the outskirts of the city, Andriy Yermak the head of the Ukrainian Presidential Office said.

A restaurant and a hotel were badly damaged as a result of the strikes, according to officials.

Crews continued to dig through the rubble to search for victims throughout the evening.

"Each such manifestation of terror proves over and over again to us and to the whole world that Russia deserves only one thing as a result of everything it has done - defeat and a tribunal, fair and legal trials against all Russian murderers and terrorists," Ukrainian President Volodymyr Zelenskyy said in a statement.

-ABC News' Fidel Pavlenko and Ellie Kaufman

The U.S. announced additional sanctions targeting the Wagner Group, specifically going after gold companies and a Russian man it says are illicitly funding the Wagner Group’s operations in Ukraine and Africa.

Central African Republic based companies Midas Resources SARLU and Diamville SAU, Dubai based company Industrial Resources General Trading and Russia based company Limited Liability Company, re connected to Wagner’s leader Yevgeny Prigozhin, who is already subject to U.S. sanctions along with numerous other entities linked to the Wagner Group, according to the Department of the Treasury’s Office of Foreign Assets Control.

Andrey Nikolayevich Ivanov, a Russian national, and an executive in the Wagner Group, allegedly worked closely with Prigozhin’s entity Africa Politology and senior Malian government officials on weapons deals, mining concerns, and other Wagner Group activities in Mali, OFAC said.

"The Wagner Group funds its brutal operations in part by exploiting natural resources in countries like the Central African Republic and Mali," Brian Nelson, the U.S. under secretary of the treasury for terrorism and financial intelligence, said in a written statement. "The United States will continue to target the Wagner Group’s revenue streams to degrade its expansion and violence in Africa, Ukraine, and anywhere else."

-ABC News' Ben Gittleson

The United States is standing by the NATO communique released Tuesday and its language around Ukraine joining the alliance, despite criticism from Ukrainian President Volodymyr Zelenskyy over the lack of a timeline to do so.

"The United States clearly joined with NATO allies in agreeing to a strong positive message reaffirming that Ukraine will become a member of the alliance," U.S. National Security Council Senior Director for Europe Amanda Sloat said during a press briefing in Lithuania's capital on Wednesday morning, on the final day of a high-stakes NATO summit. "And as the communique has made clear, as the president has spoken to directly in the past, we recognize that Ukraine has already made significant progress in terms of reforms. That was part of what led to allies making the decision to say that the Membership Action Plan was no longer required for Ukraine."

"But as both the president has said and as the communique made clear, there is still the need for Ukraine to take further democratic and security sector reforms," she added.

Sloat told reporters that the U.S. has been and would continue to work with Ukraine both bilaterally and through the NATO alliance to ensure that the reforms required to join the alliance are met.

When asked to respond to Zelenskyy's criticism that the lack of a timeline was "unprecedented and absurd," Sloat defended the agreement as a significant one.

"I would agree that the communique is unprecedented, but I see that in a positive way. We joined with allies yesterday in agreeing to a very strong, positive message. We reaffirmed that Ukraine will become a member of the NATO alliance," she said, arguing that removing the Membership Action Plan requirement for Ukraine was a "very significant" step on NATO's part.

-ABC News' Molly Nagle