A deal aimed at ending a lethal spiral of violence in Ukraine began to show serious strains late Friday just hours after it had been signed.
Angry protesters shouted down opposition members of Parliament who negotiated the accord, and a militant leader threatened armed attacks if President Viktor Yanukovych did not step down by this morning.
Russia, which joined France, Germany and Poland in mediating the settlement, introduced a further element of ominous uncertainty by declining to sign the agreement, which reduces the power of Yanukovych, a firm ally of Moscow. This stirred fears that Moscow might now work to undo the deal through economic and other pressures, as it did last year to subvert a proposed trade deal between Ukraine and the European Union.
U.S. officials said President Vladimir Putin told President Barack Obama in a telephone call Friday that he would work toward resolving the crisis.
The United States, Russia and the 28-nation EU are deeply concerned about the future of Ukraine, a divided nation of 46 million. The country's western regions want to be closer to the EU and have rejected Yanukovych's authority in many cities, while eastern Ukraine favors closer ties with Russia.
The developments cast a shadow over a hard-fought accord that mandates early presidential elections by December, a swift return to a 2004 constitution that sharply limited the president's powers and the establishment within 10 days of a "government of national trust." In a series of votes that followed the accord and reflected Parliament's determination to make the settlement work, lawmakers moved to free Yanukovych's imprisoned rival, former Prime Minister Yulia Tymoshenko, grant blanket amnesty to all antigovernment protesters and provide financial aid to the hundreds of wounded and families of the dead.
Aside for a series of loud explosions Friday night and angry chants in the protest encampment, Kiev was generally quiet. And the authorities, although previously divided over how to handle the crisis, seemed eager to avoid more confrontations. By late in the afternoon, all police had vacated the government district of the capital, leaving behind burned military trucks, mattresses and heaps of garbage at the positions they had occupied for months.
On Independence Square, the focal point of the protest movement, however, the mood was one of deep anger and determination, not triumph.
"Get out, criminal! Death to the criminal!" the crowd chanted, reaffirming what, after a week of bloody violence, has become a non-negotiable demand for many protesters: the immediate departure of Yanukovych.
When Vitali Klitschko, one of the three opposition leaders who signed the deal, spoke in its defense, people screamed, "Shame!" A coffin was then hauled onto the stage to remind him of the more than 70 people who had died during violence Thursday, the most lethal day of political mayhem in Ukraine since independence from the Soviet Union more than 22 years ago.
The violence escalated the urgency of the crisis, which began with the protests in late November after a decision by Yanukovych to spurn a trade and political deal with the European Union and tilt his nation toward Russia instead.
It was difficult to know how much of the fury voiced Friday night in Independence Square was fiery bravado, a final cry of anger before the 3-month-long protest movement winds down or the harbinger of yet more and possibly worse violence to come.
Vividly clear, however, was the wide gulf that had opened up between the opposition's political leadership and a street movement that has radicalized and slipped far from the already tenuous control of politicians.
Dmytro Yarosh, leader of the Right Sector, a coalition of hard-line nationalist groups, reacted defiantly to news of the settlement, drawing more cheers from the crowd.
"The agreements that were reached do not correspond to our aspirations," he said. "Right Sector will not lay down arms. Right Sector will not lift the blockade of a single administrative building until our main demand is met — the resignation of Yanukovych."
He added that he and his supporters are "ready to take responsibility for the further development of the revolution." The crowd shouted: "Good! Good!"
Eric Fournier, France's representative at the talks, cautioned that Friday's deal was "a beginning, not an end. There is still a lot of anger around."
The pressure for a political settlement has been intense, coming not only from European governments but from a widespread fear among the population that this former Soviet republic of 46 million people was hurtling toward a possible civil war.
In a sign that the accord could yield concrete results, Parliament, long dominated by the president's Party of Regions, passed a law that would allow the release from prison of Tymoshenko, an opposition leader who was incarcerated after she lost the 2010 presidential election to Yanukovych.
"Free Yulia! Free Yulia!" lawmakers chanted.
It was unclear when she might be freed from a penitentiary in eastern Ukraine. Yanukovych must still sign that bill into law, and then Tymoshenko's lawyers would have to ask the court for her release from prison in the eastern city of Kharkiv.
As happened with previous deals, the concessions made by Yanukovych were seen by many protesters as too little, too late.
Even more moderate opponents of the president want him gone and even dead. Unless he resigns, Yuriy Korshenko, a lawyer and former judge, said, "He will end up like Ceausescu and Gadhafi." The Romanian and Libyan dictators, Nicolae Ceausescu and Moammar Gadhafi, were killed in bloody uprisings against their rule.
Deal between President Yanukovych and opposition leaders calls for:
• Ukrainian authorities to name a new unity government within 10 days.
• Early elections no later than December, rather than next March.
• Protesters to hand over weapons, withdraw from buildings they have occupied and take down the camps they have erected around the country.
• Restored the 2004 constitution that limits presidential authority.
• Fired Interior Minister Vitali Zakharchenko, who is blamed for ordering police violence, including the snipers who killed scores of protesters.
• Decriminalized the charge under which former Prime Minister Yulia Tymoshenko was imprisoned.