Russian forces have killed at least 16 children during their invasion of Ukraine, Healthcare Minister Viktor Liashko said Sunday.

The remarks, from the minister's verified Telegram channel, followed those of Ukraine Foreign Minister Dmytro Kuleba, who detailed what he described as Russian "war crimes" in a press briefing earlier Sunday, alleging children had been killed in recent days. Russian troops on Friday assaulted an orphanage with 50 children inside, as well as a kindergarten, Kuleba said.

Health Minister Oleh Liashko said in a Facebook post Saturday that three children were among the 198 Ukrainians who have died since the attack began Thursday. He added that 1,115 had been wounded, 33 of whom were children.

NBC News has not independently verified the figures.

As Russian troops draw closer to the Ukrainian capital, Kyiv’s mayor is filled with pride over his citizens’ spirit yet anxious about how long they can hold out.

In an interview with The Associated Press on Sunday, after a grueling night of Russian attacks on the outskirts of the city, Mayor Vitali Klitschko was silent for several seconds when asked if there were plans to evacuate civilians if Russian troops managed to take Kyiv.

“We can’t do that, because all ways are blocked,” he finally said, speaking in English. “All ways are blocked and right now we are encircled — everywhere is Russians and we don’t have a way to evacuate the people. And everyone who had plans to evacuate himself already moved.”

The AP was not able to immediately verify the mayor’s report that Kyiv was surrounded, and his spokesperson later tweeted that the mayor had misspoken.

Klitschko himself later backed away from his earlier assessment, saying on his Telegram channel that “In the evening, Russian Internet publications spread information with reference to me that Kyiv is allegedly surrounded and evacuation of people is impossible. ... Do not believe lies! Trust information only from official sources.”

European leaders are in step with the U.S. over the decision to target assets owned by Russian oligarchs as well as sanctioned companies in retaliation for Putin's invasion of Ukraine, a senior White House official said. 

The Biden administration plans to launch a transatlantic task force to identify any "ill-gotten gains" from elites close to Putin and the Russian government, the official said. This is in addition to severe sanctions placed on Putin's personal assets and the limitations on Russian banks. 

"We’ve also sanctioned Russian oligarchs and Putin’s inner circle and their family members, including Putin’s cronies who sit atop Russia’s largest financial institutions and are responsible for providing the resources necessary to support Putin’s further invasion of Ukraine," the official said.

Russia's central bank said Thursday that it would offer assistance to any banks or businesses facing sanctions, after the ruble plummeted in value against the U.S. dollar.

The U.S. and its allies announced Saturday that they would limit Russia's access to SWIFT, a service that facilitates global transactions among thousands of financial institutions. That decision, along with sanctions on Russian banks, Putin, and Putin's inner circle, is designed to tighten the financial straits on Putin's war reserves. 

Ukraine's national police service said Sunday that it was working with volunteers to launch cyberattacks on Russian and Belarusian websites.

In a Facebook post to its verified page, the police service said many major websites were unavailable. 

"The website of the Investigative Committee of the Russian Federation, the FSB of the Russian Federation, Sberbank and other important government and critical information systems for the Russian Federation and Belarus are currently down," the police service said.

Various Russian websites have experienced intermittent outages in recent days, and Ukraine has called for volunteers who wish to help Ukraine both defend its own infrastructure and help with attacks on Russia.

Numerous distributed denial of service (DDoS) attacks, in which hackers overwhelm websites with traffic, targeting both Russian and Ukrainian websites, have been tracked in recent weeks.

BP, the big British oil company, said Sunday that it was ending its business relationship with Rosneft, a Russian oil and gas company.

BP said in a news release that it would divest its 19.75 percent stake in Rosneft and that its CEO, Bernard Looney, was resigning from Rosneft's board.

The high-profile move severs one of the biggest financial relationships between Russia and the West.

"BP has operated in Russia for over 30 years, working with brilliant Russian colleagues," BP chair Helge Lund said in the news release. "However, this military action represents a fundamental change. It has led the BP board to conclude, after a thorough process, that our involvement with Rosneft, a state-owned enterprise, simply cannot continue."

Ukrainian Foreign Minister Dmytro Kuleba put out a fresh call Sunday for the weapons that have been crucial to the country's fight against Russia.

"We need weapons to fight to defend our country. We specifically need anti-tank, anti-air, anti-missile weapons," Kuleba said in a news conference. "We need more air-to-air and ground-to-air missiles to counter invaders. We need more drones, more vehicles, aircraft artillery, guns, machine guns, ammunition."

Russia's armored units and air power have been stymied thus far by some of the handheld weapons supplied by the West: Javelin and NLAW anti-tank missiles and stinger anti-aircraft missiles. These are relatively simple and easy-to-use weapons that can be fired by individuals and have been used in previous conflict to great effect. Stinger missiles in particular are well known for their role in Afghanistan's resistance against Russia in the 1980s.

In a major reversal of its previous stance, Germany said Saturday it would be contributing anti-tank and Stinger missiles to the Ukrainian cause.

Barry McCaffrey, a retired four-star general and MSNBC contributor, said, "You can take an average civilian and in one hour have them perfectly capable of operating the Javelin and the effectiveness is likely to be in excess of 90 percent first-round hit."

"And to boot, since you don't have to guide it all the way to the target, your chance of being killed during the engagement go from extremely high to almost non-existent," he added.

The European Union is banning all travel from Russian planes over its airspace in response to President Vladimir Putin's invasion of Ukraine, European Commission President Ursula von der Leyen announced Sunday.

"We are proposing a prohibition on all Russian-owned, Russian-registered or Russian-controlled aircraft," von der Leyen said. "These aircraft will no more be able to land in, take off or overfly the territory of the E.U. This will apply to any plane owned, chartered or otherwise controlled by a Russian legal or natural person."

The ban covers any aircraft privately owned by a Russian oligarch, von der Leyen added.

Individual European countries had previously prohibited various Russian aircraft from their airspace.

The European Union announced new steps against Russia on Sunday, including the financing and delivery of arms to Ukraine and a ban on the state-owned Russia Today and Sputnik media outlets.

"For the first time ever, the European Union will finance the purchase and delivery of weapons and other equipment to a country that is under attack," European Commission President Ursula Gertrud von der Leyen said. "This is a watershed moment."

She went on to say that "in another unprecedented step, we will ban in the EU the Kremlin's media machine."

"The state-owned Russia Today and Sputnik, as well as their subsidiaries will no longer be able to spread their lies to justify Putin's war and to saw division in our Union," von der Leyen said.

The EU also said it was closing its airspace to all Russian airplanes.

The U.S. currently has no reason to doubt reports that Putin asked his military’s nuclear deterrent forces to be on alert, a senior defense official told NBC News on Sunday.

In a meeting televised on state television on Sunday, Putin said the decision to place the country’s nuclear weapons on increased readiness to launch was in response to “aggressive statements" from NATO leaders. There's no view yet from U.S. intelligence on how this might play out, according to the defense official.

“We believe that this is an unnecessary and escalatory one," the official said. 

Russian forces have faced fierce resistance from Ukrainians since Russia invaded the country overnight Wednesday, while also facing severe sanctions from the U.S. and its allies. It appears that Russia has put roughly two-thirds of its combat power around Ukraine, the official said, but its military seems to be losing momentum. 

There's no evidence from U.S. intelligence that Russian forces have taken any Ukrainian cities as of yet, and it appears Russia is behind schedule on where it hoped to be with its invasion plans, the official added.