U.S. Vice President Joe Biden has telephoned Ukraine's Prime Minister Arseniy Yatsenyuk to welcome the formation of a new government and pledge U.S. support as Ukraine undertakes reforms aimed at restoring the country's economic health.
A White House statement said Biden emphasized that this is an important opportunity not only to bring peace and stability to Ukraine, but also to restore Ukrainians' faith in their democratic institutions ahead of elections set for May.
Biden said the United States will offer its full support as Ukraine pursues reconciliation, upholds its international obligations, and seeks open and constructive relationships with all its neighbors.
On Thursday Ukraine's parliament approved Mr. Yatsenyuk, a popular opposition leader, as the head of the new interim government, and Mr. Yatsenyuk accused the previous government -- that of ousted President Viktor Yanukovych -- of stealing billions from the state treasury.
Mr. Yatsenyuk said $70 billion in Ukrainian government money had been sent to offshore accounts over the last three years, and that $37 billion of credit it received has disappeared, leaving Ukraine with severe financial problems.
Yatsenyuk is a pro-Western former foreign minister and economy minister. One of his first major jobs is preventing the Ukrainian economy from collapse.
The International Monetary Fund and European Union are sending teams to Ukraine to assess the country's needs. The United States also is considering $1 billion in loan guarantees.
Earlier Thursday, the Kremlin sent Russian fighter jets to patrol its border with Ukraine -- a day after announcing large-scale military exercises in the area.
U.S. Secretary of State John Kerry said he spoke to Russian Foreign Minister Sergei Lavrov, who assured him that the exercises were previously scheduled. Lavrov repeated Russia's pledge to respect Ukrainian sovereignty.
But Kerry said "everybody needs to step back and avoid provocation."
Gunmen seized control of government buildings in Crimea -- a Ukrainian region with strong ties to Moscow and home to a Russian naval base in Sevastopol. The gunmen raised the Russian flag.
Acting Ukrainian President Oleksandr Turchyno warned that any movement of Russian forces outside the base would be considered "military aggression."
The Crimean parliament voted Thursday to dismiss the regional government and hold a referendum to determine Crimea's status in Ukraine. The referendum is set for May 25, the same day Ukraine will hold a presidential election.
In Brussels, NATO Secretary General Anders Fogh Rasmussen called the seizure of the buildings in Crimea dangerous and irresponsible. He called on Russia to avoid any action that could lead to what he called a "misunderstanding." Fogh Rasmussen also urged Ukraine's new leaders to establish an inclusive political process.
Russian news agencies report that Moscow has approved President Yanukovych's request for personal security "on Russian territory." They give no details. They also report that Mr. Yanukovych will hold a news conference Friday in the southern Russian city of Rostov-on-Don.