Russia-Ukraine updates: US to ban Russian carriers from its airspace

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

The International Olympic Committee said its executive board is recommending prohibiting athletes and officials from Russian and Belarus in international competitions.

The recommendation is "to protect the integrity of global sports competitions and for the safety of all the participants," the IOC said.

Switzerland is breaking from its longstanding policy of neutrality by adopting the packages of sanctions imposed by the European Union citing Russia's continuing military invasion of Ukraine.

Switzerland, which has long been a safe haven for Russian assets, announced on Monday that it's imposing financial sanctions targeting Russian President Vladimir Putin, Russian Prime Minister Mikhail Mishustin and Russian Foreign Ministry Sergey Lavrov, and is targeting the assets of certain people and companies.

Switzerland also is imposing entry bans against individuals who have a connection to Switzerland and are linked to Putin and will be closing Swiss airspace to flights from Russia, with the exception of flights for humanitarian, medical or diplomatic purposes, officials said.

Switzerland will also extend a ban on imports, exports and investments concerning Crimea and Sevastopol, which has been in place since 2014, to the Ukrainian regions of Donetsk and Luhansk.

Swiss officials said they are partially suspending the 2009 agreement on visa facilitation for Russian nationals, and those with diplomatic passports will continue to be allowed entry without a visa in an effort to continue diplomatic talks.

-ABC News' Christine Theodorou