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.

Russian President Vladimir Putin acknowledged Russian military losses from its ongoing invasion of Ukraine during his annual meeting with the federal security service Tuesday.

"Unfortunately, comrade officers, we know that there are losses in our ranks," Putin said.

Putin called on the FSB to provide "support" to the families of soldiers who have died in the war.

"We will always remember their heroism and bravery," he added.

Putin did not say how many soldiers have died in the war and the Russian Ministry of Defense hasn't disclosed an exact number of losses since September 2022 when Defense Minister Sergey Shoigu said just shy of 6,000 troops had died.

Secretary of State Antony Blinken and other State Department officials said Russia has likely suffered 200,000 injured or dead soldiers since the start of the war.

Putin also called on the FSB to make sure its border guard "undertake special efforts to control the Russian state border with Ukraine."

A "special group" is currently deployed at the Russia-Ukraine border, made up of border agencies, the FSB air arm, the Russian Armed Forces and the Russian National Guard, according to Putin.

"Your mission is to prevent any incursions by sabotage groups and stop any attempts to smuggle weapons and ammunition into Russia," Putin told the FSB board.

-ABC News' Tanya Stukalova and Anastasia Bagaeva