The State Department said in a statement Monday that "reports of human rights abuses have been widespread" since Russia's invasion of Ukraine, pointing to attacks that killed civilians, including children, and destroyed schools, hospitals and homes.

The allegation of human rights abuses has also gone further to accusations of war crimes by Russia's military. Amnesty International reported Sunday that Russia used cluster munitions in an attack against a kindergarten that killed three civilians, including one child, which "could constitute a war crime," the human rights group said. The use of cluster munitions against civilians is a violation of international law.

Ukrainian Foreign Minister Dmytro Kuleba has repeatedly accused Russian forces of committing war crimes, tweeting on Friday that Ukraine's general prosecutor's office is collecting reports and will send them to The Hague, adding, "responsibility is inevitable."

Secretary of State Antony Blinken will address the United Nations Human Rights Council on Tuesday. Russian Foreign Minister Sergey Lavrov was set to address the same chamber but his trip was canceled “due to an unprecedented ban on his flight in the airspace of a number of EU countries," Russia's mission to the U.N. offices in Geneva said.

-ABC News' Conor Finnegan

Talks between a Ukrainian delegation and Russian officials at the Belarus-Ukraine border have ended after six hours. Both sides will return to their capital cities for consultation ahead of a second round of talks.

Ukraine said it wanted a ceasefire and Russian withdrawal, while the Kremlin said it would not announce its position. Russia's negotiators have talked of striking a deal that's in the interests of both sides.

-ABC News' Joe Simonetti

Russian forces are frustrated by their slow advance, but that could lead them "to be more aggressive and more overt in both the size and scale of their targeting of Kyiv," a senior U.S. defense official said Monday, implying less discriminate attacks with more danger to civilian populations.

The Russians heading south to Kyiv continue to be slowed by fuel shortages and stiff Ukrainian resistance and have only moved about three miles since Sunday, leaving them about 16 miles away from the capital city, the official said.

"We believe they want to encircle Kyiv and it's possible that they could adopt siege tactics there," the official warned. On Sunday the same official said there were indications Russian forces were adopting siege tactics around the city of Chernihiv in northern Ukraine.

So far, the Russians have fired more than 380 missiles, the official said.

Putin has committed about 75% of the more than 150,000 forces he had arrayed at the border to the invasion inside Ukraine, according to the official.

There's no indication Belarusian forces are involved or are preparing to join Russia in the invasion, and Russia has not placed nuclear weapons in Belarus, according to the official.

-ABC News' Matt Seyler

According to the Elysée, Russian President Vladimir Putin told French President Emmanuel Macron on Monday that he's willing to stop strikes against civilian targets.

Putin also told Macron he's willing to preserve civilian infrastructure to secure main roads, including the road south of Kyiv, according to the French government.

Macron and Putin will speak again this week, the Elysée said.

-ABC News' Ibtissem Guenfoud