The Russians remain largely stalled on day 23 of the invasion of Ukraine and haven't moved further toward Kyiv, according to a senior U.S. defense official.

Reports of missile strikes near Lviv's airport seem accurate, the official said, adding that there was no additional information at this time.

Russians stalled on the battlefield by Ukrainian resistance are resorting to artillery and long-range missiles to strike at Ukraine’s cities. Russians have now launched 1,080 missiles at Ukrainian targets -- an increase of 80 missiles in one day, the official said.

-ABC News' Luis Martinez

During the meeting Russia convened to air its allegations of dangerous biolabs in Ukraine, U.S. Ambassador to the U.N. Linda Thomas-Greenfield told her fellow Security Council members that they may be witnessing one of Moscow’s battle tactics unfolding before their eyes.

“I will reiterate the United States’ deep and serious concern that Russia's calling for this meeting is -- is --a potential false flag effort in action. Russia has repeatedly -- repeatedly--accused other countries of the very violations it plans to perpetrate,” she stated. “We continue to believe it is possible that Russia may be planning to use chemical or biological agents against the Ukrainian people.”

“Last week we heard from the Russian representative a tirade of bizarre conspiracy theories. This week, we're hearing a whole lot more where that came from -- things that sound like they were forwarded to him on a chain email from some dark corner of the internet," she said.

"President Joe Biden has a word for this kind of talk: malarkey,” Thomas-Greenfield continued, again flatly denying claims that Ukraine has a biological weapons program. Thomas-Greenfield reminded the room that it is Russia that maintains such a program in violation of international law and has a documented history of using nerve agents against enemies of the Kremlin as well as supporting the use of chemical warfare in Syria.

“We aren't going to dignify Russia's disinformation or conspiracy theories. But we will continue to sound the alarm and tell the world where we think Russia is heading,” she added. “And we will remind the world that Russia has repeatedly -- repeatedly -- lied to this council over recent weeks."

-ABC News' Shannon Crawford, Zoha Zamar

Russian presidential aide Vladimir Medinsky, Russia’s lead negotiator in talks with Ukraine, said the two sides have made the most progress on the question of Ukraine’s “neutral status” during the negotiations, but that “nuances” remain around issues of security guarantees for Ukraine if it gives up joining NATO.

The “nuances are connected with what kind of security guarantees Ukraine gets in addition to ones it already has, in the case of renouncing joining the NATO bloc,” Medinsky told Russian media.

Medinsky said the two sides were “somewhere halfway” to meeting each other over the issue of Ukraine’s “demilitarization."

“As for demilitarisation, I would say it’s 50-50. The issues is I am now authorised to divulge any details of the negotiations and I will not do that, nor concrete figures, nor arguments of the sides, but in this part we are somewhere halfway,” he said.

-ABC News' Patrick Reevell

At a massive concert in Moscow on Friday in support of Russia’s invasion of Ukraine, Russian President Vladimir Putin called the main goal of the military special operation to stop the genocide of the population of Donbass -- a false claim Putin has been spreading.

“It is precisely to save people from this suffering, from this genocide that is the main, main reason, motive and goal of the military operation that we launched in the Donbass and Ukraine,” Putin told the packed crowd in the city’s main stadium.

The concert was timed to mark the eight-year anniversary of Russia’s annexation of Crimea from Ukraine.

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler