Turkey is beginning the process of ratifying Finland's application to join NATO, Turkish President Recep Tayyip Erdogan said Friday, 10 months after both Finland and Sweden applied to become NATO members in the wake of Russia’s invasion of Ukraine.

"At a critical time for our security, this will make our alliance stronger and safer," NATO Secretary General Jens Stoltenberg said in a statement.

The breakthrough came as Finnish President Sauli Niinisto was in Ankara, Turkey, to meet with Erdogan.

Erdogan said Finland fulfilled its part of the agreements and therefore he saw no reason to further delay the ratification process. Erdogan did not provide an update on Sweden's bid.

National security adviser Jake Sullivan said in a statement, "We encourage Türkiye to quickly ratify Sweden’s accession protocols as well. In addition, we urge Hungary to conclude its ratification process for both Finland and Sweden without delay. … The United States believes that both countries should become members of NATO as soon as possible."

-ABC News' Will Gretsky

The International Criminal Court has issued an arrest warrant for Russian President Vladimir Putin, saying in a statement Friday that Putin is "allegedly responsible for the war crime of" unlawfully deporting children from occupied areas of Ukraine and bringing them to Russia.

The ICC also issued an arrest warrant for Maria Lvova-Belova, Russia's presidential commissioner for children's rights, alleging she carried out the same war crime.

Russian Foreign Ministry spokeswoman Maria Zakharova said in a statement that the arrest warrants "have no meaning for the Russian Federation" and "are legally null and void."

Andriy Yermak, head of the Office of the President of Ukraine, tweeted that the arrest warrants are "just the beginning."

Russia has committed a "wide range of war crimes" and possible crimes against humanity in Ukraine, according to a new United Nations-backed investigation.

"The body of evidence collected shows that Russian authorities have committed a wide range of violations of international human rights law and international humanitarian law in many regions of Ukraine and in the Russian Federation," the human rights report by the Independent International Commission of Inquiry on Ukraine stated. "Many of these amount to war crimes and include willful killings, attacks on civilians, unlawful confinement, torture, rape, and forced transfers and deportations of children."

Additionally, Russian attacks on Ukraine's energy-related infrastructure and use of torture "may amount to crimes against humanity," the report concluded.

The commission said it conducted interviews with nearly 600 people, inspected graves, destruction and detention sites and consulted satellite imagery and photographs as part of its investigation.

Poland plans to deliver four MiG-29 fighter jets to Ukraine "in the coming days," Polish President Andrzej Duda said at a press conference on Thursday.

The move will make Poland the first NATO member to supply fighter planes to Ukraine, the Associated Press reported.

The latest news shortens the timeline announced earlier this week by Polish Prime Minister Mateusz Morawiecki, who had said they might send the Soviet-designed fighter jets to Ukraine in the next four to six weeks.

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