In response to a plea on Twitter from a Ukrainian official, SpaceX CEO Elon Musk said Saturday that his high-speed internet service Starlink is now active in Ukraine.

"More terminals en route," he tweeted in a reply to Mykhailo Fedorov, Ukraine's vice prime minister and minister of digital transformation.

Earlier Saturday, Fedorov appealed directly to Musk and asked him to provide Ukraine with Starlink stations.

The terminals are small, portable satellite dishes on Earth that connect directly to Starlink satellites in space -- providing high-speed internet to rural and hard-to-reach locations. This is especially important for areas that have already lost access and could potentially help them avoid cyberattacks.

-ABC News' Gio Benitez

The White House announced further sanctions on Russia Saturday evening.

The U.S., along with the European Commission, France, Germany, Italy, the United Kingdom and Canada, are disconnecting some Russian banks from the Society for Worldwide Interbank Financial Telecommunication (SWIFT) banking network and are "imposing restrictive measures that will prevent the Russian Central Bank from deploying its international reserves in ways that undermine the impact of our sanctions," the White House said.

"This will ensure that these banks are disconnected from the international financial system and harm their ability to operate globally," the White House said in a statement.

The White House added, "We commit to taking measures to limit the sale of citizenship -- so called golden passports -- that let wealthy Russians connected to the Russian government become citizens of our countries and gain access to our financial systems."

The U.S. will also launch a trans-Atlantic task force "that will ensure the effective implementation of our financial sanctions by identifying and freezing the assets of sanctioned individuals and companies that exist within our jurisdictions."

On a call with reporters Saturday night, a senior administration official said the move to sanction the central bank will show that Russia's defense of claiming that sanctions don't hurt their economy "is a myth."

"The 600 billion-plus war chest of Russia's foreign reserves is only powerful if Putin can use it," the official said. "And without being able to buy the ruble from Western financial institutions, for example, Putin and the central bank will lose the ability to offset the impact of our sanctions. The ruble will fall even further, inflation will spike and the central bank will be left defenseless."

The Biden administration said it's also upping the fight against disinformation and "other forms of hybrid warfare."

-ABC News' Justin Ryan Gomez

Kyiv, which was a bustling, relaxed city three days ago, has now transformed to a war-time city as it braces for Russian forces.

Kyiv's mayor has imposed a 39-hour curfew beginning Saturday night, banning everyone except critical infrastructure workers from the streets. Ukrainian authorities say the curfew is to allow the city to hunt down Russian sabotage groups, get defenses organized and prevent friendly-fire incidents.

Checkpoints manned by tense, heavily armed Ukrainian soldiers are set up throughout Kyiv and authorities are setting up barricades.

The city’s lights have been dimmed, leaving an eerie silence, only punctured by the howls of air raid sirens or blasts of gunfire.

Since Friday morning there has been fighting in Kyiv's northern neighborhoods. For two nights, missiles have struck targets around Kyiv. Hundreds of people have begun sheltering in the deep subway system, sleeping on the platforms.

-ABC News' Patrick Reevell

A senior U.S. official told ABC News they've heard a Russian soldier on a radio call saying, “We don’t know who to shoot -- they all look like us.”

The official also said some Russian forces are disoriented, realizing the battles against Ukrainians are harder than they thought.

-ABC News' Martha Raddatz

Secretary of State Antony Blinken closed his remarks to the U.N. Security Council meeting by challenging the Russian Federation to "announce today -- with no qualification of equivocation or deflection -- that Russia will not invade Ukraine, stated clearly stated plainly, to the world."

"And then demonstrate it by sending your troops, your tanks, your planes back to their various can hangars and sending your diplomats to the negotiating table," he added.

Blinken laid out how the U.S. believes Russia will attack Ukraine -- but said he would welcome being wrong and for Russia to withdraw.

"Now, I'm mindful that some have called into question our information, recalling previous instances where intelligence ultimately did not bear out," he said, apparently referring to a similar address then-Secretary of State Colin Powell famously made to the Security Council presenting U.S. intelligence to justify the Iraq War. "But let me be clear, I am here today not to start a war, but to prevent one," he said, citing allies that agree with U.S. assessments.

"If Russia doesn't invade Ukraine, then we will be relieved that Russia changed course and proved our predictions wrong. That would be a far better outcome in the course we're currently on. And we'll gladly accept any criticism that anyone directs at us," Blinken said.

He continued, "Russia can still make if there's any truth to his claim that is committed to diplomacy. Diplomacy is the only responsible way to resolve this crisis"

Blinken also said that he sent a letter to Russia's Foreign Minister Sergei Lavrov earlier Thursday proposing that they meet next week in Europe following their talks in recent weeks "to discuss the steps that we can take to resolve this crisis without conflict" and that U.S. is also proposing meetings at the NATO Russia Council and the OSC Permanent Council.

"These meetings can pave the way for a summit with key leaders in the context of de-escalation to reach understandings on our mutual security concerns," he added.