Ukrainian Defense Minister Oleksii Reznikov said Friday the military is "ready" to launch a counteroffensive against Russian forces.

"It's up to the general staff and the command," Reznikov said during a press briefing in Kyiv. "We will do it as soon as there is God's will, the weather and the commanders' decision."

Ukraine has received Patriot missile defense systems from the United States as well as Germany and the Netherlands. The Ukrainian military has been trained on how to use the systems and "mastered" them within weeks, according to Reznikov.

"The exact number of batteries, I'm sorry, I won't say," he added. "Let the enemy guess."

Meanwhile, Ukrainian Foreign Minister Dmytro Kuleba urged the world not to consider or call the anticipated counteroffensive "a decisive battle." Speaking at a press conference in Odesa on Friday, Kuleba said the decisive battle is the one that will lead to the liberation of all occupied Ukrainian territories.

-ABC News’ Will Gretsky

One person was killed and 23 people, including a child, were wounded in a Russian missile strike in Mykolaiv early Thursday, Ukrainian President Volodymyr Zelenskyy said.

The missile struck a block that had apartments, houses and a historic building, according to Zelenskyy.

"The terrorists will not get away with this yet another crime against humanity," the president said in a statement.

-ABC News' Will Gretsky

Ukrainian President Volodymyr Zelenskyy spoke with Chinese President Xi Jinping in what was the two leaders' first official contact since January 2022, before Russia's invasion of Ukraine.

Xi announced that he will send a special envoy to visit Ukraine and "other countries" to work on a political solution.

"I believe that this call, as well as the appointment of Ukraine's ambassador to China, will give a powerful impetus to the development of our bilateral relations," Zelenskyy said in a statement on Twitter.

The Chinese government's official position still refuses to call the war an "invasion."

The call between the two leaders is said to have lasted an hour, according to Zelenskyy's office.

"Before the full-scale Russian invasion, China was Ukraine's number one trading partner. I believe that our conversation today will give a powerful impetus to the return, preservation and development of this dynamic at all levels," Zelenskyy said in a statement.

-ABC News' Karson Yiu, Cindy Smith and Will Gretsky

At least two people were killed and 10 injured after a Russian missile hit a Ukrainian museum Tuesday, officials said.

The local history museum is located in the city center of Kupiansk, in the Kharkiv region.

"The terrorist country is doing everything to destroy us completely. Our history, our culture, our people," Ukrainian President Volodymyr Zelenskyy said on social media while sharing a video that showed the damaged building. "Killing Ukrainians with absolutely barbaric methods."

A Moscow court has sentenced one of Russia's best-known opposition leaders, whose family live in the U.S., to 25 years in prison in what is widely seen a show trial.

Vladimir Kara-Murza is the most high-profile opponent of Russian President Vladimir Putin to be jailed since Alexey Navalny.

Kara-Murza's extraordinarily harsh sentence is one of the lengthiest any opposition figure has received under Putin and illustrates how repressive Russia has become during the war in Ukraine, reverting to something much closer to the USSR where no opposition is tolerated.

Kara-Murza was convicted of treason, as well as "discrediting Russia's armed forces," a new law that effectively criminalizes criticizing the war in Ukraine. He was also convicted of belonging to a banned organization. The charges are widely seen as politically motivated.

Kara-Murza is one of Russia's best-known pro-democracy figures and a veteran critic of Putin.

Kara-Murza, who holds both British and Russian citizenship, spent many years living in the United States and his wife and children still live in Virginia. He was close to the late U.S. Sen. John McCain, who championed human rights in the former Soviet Union.

Dozens of journalists and Western diplomats attended the court hearing on Monday, including the U.S. ambassador who read out a statement condemning the sentence.

"We support Mr. Kara-Murza and every Russian citizen to have a voice in the direction of their country. Mr. Kara-Murza and countless other Russians believe in and hope for a Russia where fundamental freedoms will be upheld. And we will continue to share those hopes and work for that outcome," Amb. Lynne Tracy said.

Kara-Murza previously has survived being poisoned not once but twice. In 2015 and then again in 2017, he suffered organ failure after being exposed to an unknown toxin. Independent researchers later linked the poisoning to the same team of FSB poisoners who targeted Navalny.

He chose to return to Russia after the war began, believing it was important to continue to campaign for freedom in his country and has been an outspoken critic of the invasion.

His trial was held entirely behind closed doors, but a letter containing his closing statement to the court has been released to reporters.

"I only blame myself for one thing," Kara-Murza said in the statement. "I failed to convince enough of my compatriots and politicians in democratic countries of the danger that the current Kremlin regime poses for Russia and for the world."

"Criminals are supposed to repent of what they have done. I, on the other hand, am in prison for my political views. I also know that the day will come when the darkness over our country will dissipate.

-ABC News' Patrick Reevell