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

President Joe Biden on Thursday authorized "additional strong sanctions" against Russia.

"This is going to impose severe cost on the Russian economy both immediately and overtime," Biden said in an address. "We have purposefully designed these sanctions to maximize the long-term impact on Russia and to minimize the impact on the United States and our allies."

Biden said he and the other G-7 leaders are in agreement and vowed to "limit Russia's ability to do business in dollars, euros, pounds and yen to be part of the global economy."

Biden said the administration was imposing sanctions on four more major banks, meaning "every asset they have in America will be frozen," he said.

"This includes VTB, the second largest bank in Russia, which has $250 billion in assets," he said.

Biden said they're adding names to the list of Russian elites and family members the U.S. is sanctioning, as well.

"Between our actions and those of our allies and partners, we estimate that we'll cut off more than half of Russia's high-tech imports," Biden said. "We'll strike a blow to their ability to continue to modernize their military. It will degrade their aerospace industry, including their space program. It will hurt their ability to build ships, reducing their ability to compete economically. And it will be a major hit to Putin's long-term strategic ambitions."

However, Biden stopped short of personally sanctioning Russian President Vladimir Putin himself, or cutting Russia off from the SWIFT international banking system.

Biden told reporters that sanctioning Putin is "on the table."

Biden said Putin's attack on Ukraine was premeditated and had been planned for months.

"For weeks we have been warning that this would happen, and now, it's unfolding largely as we predicted," he said.

"Putin is the aggressor. Putin chose this war. And now he and his country will bear the consequences," Biden said.

The U.S. Treasury Department in a statement said it's "taking action against Russia’s top financial institutions, including sanctioning by far Russia’s two largest banks and almost 90 financial institution subsidiaries around the world."

The department said it's also "sanctioning additional Russian elites and their family members and imposing additional new prohibitions related to new debt and equity of major Russian state-owned enterprises and large privately owned financial institutions."

"This will fundamentally imperil Russia’s ability to raise capital key to its acts of aggression," the department said. "These actions are specifically designed to impose immediate costs and disrupt and degrade future economic activity, isolate Russia from international finance and commerce, and degrade the Kremlin’s future ability to project power."

Secretary of Defense Lloyd Austin, at the direction of the president, has ordered 7,000 more U.S. troops to Germany "to reassure NATO Allies, deter Russian aggression and be prepared to support a range of requirements," a senior defense official said.

The troops are expected to deploy in the coming days, the official said.

-ABC News' Matt Seyler

There are movements of Russian military and special forces coming into Ukraine from many directions, according to the officials: from the northeast via Russia; from the south via Moscow-annexed Crimea; and from the north via both Belarus and Russia.

U.S. intelligence believe these three axes were "designed to take key population centers" and that the early moves from the north toward Kyiv indicate an intention to remove the Ukrainian government, a senior U.S. defense official told reporters at the Pentagon.

"What we're seeing are initial phases of a large-scale invasion," the official said.

The initial attack included an estimate of more than 100 Russian-launched missiles -- mostly short-range ballistic missiles but also some medium-range ones -- and about 75 fixed-wing heavy and medium bombers. So far, the targets are mostly Ukrainian military infrastructure and air defense systems, the official said, adding that U.S. intelligence does not yet have a good sense of total damages or casualties.

The official could not give an exact estimate of how many Russian troops have crossed into Ukraine thus far but said that, at this early stage, it is certainly a minority of the 150,000 troops that were massed near the borders.

U.S. intelligence have seen indications that Ukrainian troops "are resisting and fighting back," the official said. Some fighting has been seen around the airport in Kyiv. But the heaviest fighting is currently occurring in the northeastern city of Kharkiv, some 300 miles east of Kyiv, according to the official.

"We have not seen the Russians thus far move into the western part of Ukraine," the official said. "We don't know exactly where things are going to unfold."

The U.S. official said Russia has conducted "ground incursion from Belarus to the northwest of Kyiv, and we have seen at least some indications of air assault incursions into Kharkiv."

"So missile, long range fires, and then there has been some insertion of troops both from the air and on the ground in the north," the official summarized.

"We haven't seen a conventional move like this, nation state to nation state [in Europe], since World War II," the official said, "It has every potential to be very bloody, very costly and very impactful on European security writ large."

The official said he did not have a number on casualties.

-ABC News' Matt Seyler

Ukraine has lost control of a key military airport that is located less than 20 miles from the center of the capital Kyiv, according to Ukraine’s deputy interior minister.

Russian special forces landed at the Hostomel airport just on the edge of Kyiv earlier Thursday and after fierce fighting the base remains in Russian hands, deputy minister Anton Gerashchenko said.

-ABC News' Patrick Reevell