The Pentagon has been providing daily updates on the Russian invasion of Ukraine and Ukraine's efforts to resist.
Here are highlights of what a senior U.S. defense official told reporters on Friday:
Russia flying 20 times as many sorties as Ukraine
Russian military planes are flying an average of 200 sorties per day, compared to only about 10 per day flown by Ukraine, according to the official.
Much of the airspace above Ukraine is heavily guarded by both Ukrainian and Russian surface-to-air missiles, making air operations risky for both sides.
But Russian aircraft don't have to enter Ukrainian airspace to do damage.
"You can launch cruise missiles from aircraft from a great distance away. And if your target is relatively close, you don't need to enter the airspace," the official said.
For the first time, the official gave details on the total number of functioning Ukrainian fighter jets and how much they're being used.
"They have 56 available to them now, fully operational, and they're only flying them five to 10 hours a day," the official said.
Ukraine needs drones, not jets: Official
Noting Russia's vast umbrella of anti-aircraft capability over Ukraine and its larger air force, the official repeated some of the arguments we heard from the Pentagon earlier this week about the relative ineffectiveness of sending more aircraft to Ukraine.
"It makes little sense to us that additional fixed-wing aircraft is going to have somehow solve all these problems. What they need are surface-to-air missile systems, they need MANPADS, they need anti-armor, and they need small arms and ammunition, and they need these drones, because that's what they're using with great effect. And so, that's what we're focused on," the official said.
Ukrainian forces are making "terrific" use of drones, especially against Russian ground movements, according to the official. The drones can be also used both for reconnaissance and surveillance.
"They're trained on how to use them, they can fly below radar coverage by the Russians," the official said.
They are also much cheaper than fighter aircraft, and being unmanned, don't risk pilots being killed or captured.
Chemical weapons and false flags
The official said that despite claims from China and Russia, the U.S. is not helping Ukraine create or use any chemical or biological weapons.
"This is bio research with regard to two things: One, helping Ukraine over the years decrease the pathogen inventory that they had under Soviet years, and then to develop strategies to defeat pathogens going forward," the official said. "It's scientific research, it's not bio-weapons capabilities."
The official said the U.S. has nothing to hide, and that information on its role in scientific work in Ukraine was already publicly available.
"The only reason why we elevated the discussion is because the Russians and the Chinese decided to lie about it -- just flat out lie," the official said.
The official would not offer any U.S. intelligence assessment of the likelihood of Russian President Vladimir Putin deploying chemical or biological weapons in Ukraine.
"We know that the Russians have had -- and we assess that they still have -- a sophisticated chemical and biological weapons program. I'm not going to talk about intelligence assessments about what they may do with that program or what, if any, designs they might have on Ukraine in that regard," the official said.
The official said Russia's "ridiculous narrative" could possibly "be building a pretext for some sort of false flag event."
State of the invasion
The push to Kyiv: Russians have not moved any closer to Kyiv from the northwest since yesterday, still approximately 9 miles from city center. But the U.S. has seen rear elements move up closer to those advance troops. Russians advancing on the capital from northeast now 12-19 miles out.
Pentagon press secretary John Kirby told reporters Friday that the Russians coming from the east, while further from Kyiv, are gaining more ground than those to the northwest near the Hostomel Airport.
"We do assess that the Russians are beginning to make more momentum on the ground towards Kyiv, particularly from the east, not quite so much from the north," Kirby said.
Kharkiv: Russians are "closing in," but the city is well defended and hasn't been taken yet.
Mariupol: The port city is under increasing pressure today. It is surrounded from northeast and southwest, under heavy bombardment, but Ukrainians are fighting back there.
Kherson: The city remains under Russian control: "We continue to assess that they have Kherson," the official said.
Mykolayiv: Russian forces remain to the northeast of the city, though it is under increasing pressure. "We've observed the Ukrainians are continuing to defend the city, and the Russians are just outside the city," the official said.
Lutsk and Ivano-Frankovsk: The Russians struck airfields in each city Friday.
"Obviously, they wanted to eliminate the Ukrainians' ability to use these airfields," the official said.
The official did not know how much the Ukrainians were using these two airfields or how extensive the damage was.
"What's unusual about it is that [the Russians] haven't been striking in western Ukraine," the official said of the strikes.
Russian missile strikes
The Russians have now launched nearly 810 missiles against Ukraine -- almost half have been fired from within Ukraine using mobile platforms. The rest have been fired from Russia, Belarus, and a small number from the Black Sea. This is up from an estimate of 775 missiles offered by the official Thursday.
Majority of combat power intact
Russia still has roughly 90% of its invading combat power still viable, with Ukraine falling just under 90%, the official said.