President Barack Obama called Russian President Vladimir Putin Friday, the White House said as it welcomed Russia's involvement in an agreement signed today between Ukrainian President Viktor Yanukovych and opposition leaders.
The White House says the two presidents "exchanged views on the need to implement quickly the political agreement reached today in Kyiv, the importance of stabilizing the economic situation and undertaking necessary reforms, and the need for all sides to refrain from further violence."
A senior State Department official called the call "clearly an important signal" that the two presidents -- at odds on several world issues -- were able to talk "positively" about the agreement.
The official, who spoke on a condition of anonymity to discuss the talks, said the conversation was "completely constructive and workman-like on the way forward."
The official said the U.S. considers "it constructive that -- that Putin has been engaged, not just with us, but also with European leaders as this has gone forward, and that he chose to avail himself of the opportunity to participate, which gives us an opportunity to work together, to implement going forward."
The White House has called on Russia to end its support for Syrian leader Bashar Assad and the White House says the two presidents talked about the ongoing violence in Syria, "including the importance of efforts to advance a political solution, concerns over the humanitarian crisis and the necessity of a strong UN Security Council resolution on the issue, and the need for the Assad regime to adhere to its commitment to eliminate Syria’s chemical weapons program."
In addition, the White House said, they discussed U.S.-Russian cooperation on talks aimed at persuading Iran to give up its nuclear weapons ambitions.
And, the White House says, Obama "congratulated Russia on its hosting of the Olympic games."
The two leaders spoke for about an hour, Deputy National Security Advisor Ben Rhodes told MSNBC's "NOW with Alex Wagner."
Press Secretary Jay Carney said earlier that Russia's efforts to back the cease fire and the agreement were "obviously welcome."
"We welcome the cessation of violence and we welcome the agreements that have been reached," Carney said. "We're still at an implementation stage, and we monitor this very closely."
Dozens had died in street violence this week, capping three months of clashes between Yanukovych's security forces and protesters unhappy over the government’s decision in November to forgo a trade deal with the European Union in favor of a $15 billion bailout from Russia.
In the MSNBC interview, Rhodes said the two presidents talked about the situation in Ukraine and Obama "underscored that we have a significant opportunity with this cease-fire, with this agreement, that would bring in a coalition government, that would reform the constitution to reduce the power of the presidency and that would move to early elections."
Rhodes said the agreement "holds the promise of reducing tensions and giving a pathway toward a democratic outcome here, which is in our interests and in the interests of the Ukraine people."
He said the Russians recognize that instability on their border "is not a good thing. And the fact is, there is going to be instability unless the Ukrainian people feel like their aspirations are being met."
He reiterated the administration's stance that it would move to "greater consequences" if the agreement falks apart and the country turns violent. The U.S. has imposed some sanctions with travel bans on Ukraine officials.
"We stand very ready to move to additional sanctions if we see the need to enforce accountability for the violence that has taken place and if this type of agreement does not get enforced," Rhodes said.
The White House in an earlier statement noted the agreement was reached after talks overseen by foreign ministers from Germany, Poland and France and was overseen by Russia. And it called the agreement "consistent with what we have advocated in calling for a de-escalation of the violence, constitutional change, a coalition government, and early elections."
"We support the efforts of all those who negotiated this agreement, commend the courageous opposition leaders who recognized the need for compromise, and offer the support of the United States in its implementation," the White House said in the statement. "Now, the focus must be on concrete action to implement this agreement, which we will be monitoring closely. In this regard, we call for immediate implementation of the initial steps -- an end to the violence, amnesty and security normalization, and passage of the constitutional package in the Rada -- to provide space for the negotiations to begin on formation of a technocratic coalition government.
"Respect for the right of peaceful protest –- including on the Maidan –- is essential. As we have said, there must be accountability for those responsible for the violence and the casualties that have resulted since the crisis began, and we remain prepared to impose additional sanctions as necessary. The United States stands with the Ukrainian people as they work to restore peace, security, and human dignity across the country and determine the future course of their nation."