President Joe Biden announced additional sanctions that "will impose severe costs on the Russian economy" following its invasion of Ukraine.
"Putin is the aggressor. Putin chose this war and now he and his country will bear the consequences," Biden said from the White House Thursday.
The new sanctions will target Russian banks, oligarchs and high-tech sectors
Earlier, a U.S. Defense official said Russia has "every intention" of overthrowing the Ukrainian government with President Vladimir Putin's invasion of the neighboring country on Thursday.
Russia Intends to Overthrow Ukraine Government, US Says
"What we are seeing is initial phases of a large-scale invasion," a senior Pentagon official told reporters. "They're making a move on Kyiv."
"They have every intention of decapitating the Ukraine government," the official said.
The official said the first Russian assault involved more than 100 short-range ballistic missiles, but also medium-range ballistic missiles, cruise missiles and surface-to-air missiles. The missiles were targeted at military sites -- airfields, barracks and warehouses.
Map: Russian Attacks in Ukraine
The United States has "seen indications" that Ukrainian troops "are resisting and fighting back," the official said.
Putin launched the invasion early Thursday in the biggest European onslaught since the end of World War II, attacking Ukrainian forces in the disputed eastern region and launching missiles on several key cities, including the capital, Kyiv.
Putin called it a "special military operation" aimed at the "demilitarization and denazification" of its southern neighbor, once a Soviet republic but an independent country since 1991.
Some information came from The Associated Press, Agence France-Presse, and Reuters.