NEWPORT, Wales (USA TODAY) -- At the close of a two-day NATO summit, President Obama said Friday he was skeptical, that a new cease-fire in Ukraine would hold and announced a new round of sanctions against Russia in case a permanent peace deal fails.
The president also praised the firmness by the Western alliance in confronting Russia, saying it underscored the principle that "big countries just can't stomp on little countries."He announced new sanctions against Russia that he said could be lifted if the cease-fire and a peace deal is successful in ending the fight between Ukrainian troops and pro-Russia separatists.
"The only reason that we are seeing this cease-fire at this moment is because of both the sanctions that have already been applied and because of the threat of further sanctions which are having a real impact on the Russian economy and have isolated Russia in a way that we have not seen in a very long time," Obama said.
He said that "the path for Russia to rejoin the community of nations that respect international law is still there. and we encourage President (Vladimir) Putin to take it."
Obama said NATO firmness toward Russia, including plans for a new rapid-response force for Eastern Europe, "has been a testimony to how seriously people take the basic principle that big countries can't just stomp on little countries or force them to change their policies and give up their sovereignty."
The conditional cease-fire agreement, which was signed Friday in Minsk between Ukraine and pro-Russia separatists, took effect Friday afternoon.
It was not immediately clear whether the combatants, still engaged in heavy fighting early Friday near the port city of Mariupol o the Sea of Azov in southeast Ukraine, had actually ceased hostilities.
Shaun Walker, correspondent for The Guardian who is in Mariupol, said on Twitter: "As ceasefire time comes, all quiet on eastern checkpoint." The tweet, which includes a photo of Ukrainian troops with arms folded standing next to their armored personnel carrier, adds: "Azov fighters chilling, sceptical it'll last."
Ukrainian forces and separatists say they have ceased military operations, The Wall Street Journal reports.
Ukrainian President Petro Poroshenko announced the agreement to reporters in Wales and on his official web site, saying it was important that the cease-fire lasts long "and that during this cease-fire we continue political dialogue to find peace and stability."
"The highest value is human life. We must do everything possible and impossible to terminate bloodshed and put an end to people's suffering," Poroshenko said.
He said he said international observers from the Organization of Security and Cooperation in Europe would monitor the cease-fire.
Alexander Zakharchenko, head of the self-proclaimed Donetsk People's Republic, the main separatist group, confirmed that his forces also accepted the a cease-fire agreement., Reuters reports. Other rebel leaders did likewise on Twitter, the Associated Press reports.
The protocol to the 14-point peace plan includes "all aspects of control and prisoner exchange," the Interfax-Ukraine news agency reports, quoting source close to the negotiations in Minsk.
On his Facebook page, Ukrainian Prime Minister Arseniy Yatsenyuk said peace must be restored, "but it's important to know, what is the price for the peace."
He said itmust include the withdrawal of "the Russian army, Russian criminals and terrorists," and control over the border.
NATO Secretary-General Anders Fogh Rasmussen said he would "warmly welcome" the establishment of a real cease-fire.
"But it is one thing to declare a cease-fire," he said. "The next and crucial step is to implement it in good faith and it remains to be seen. But so far so good."
Earlier, Rasmussen, in announcing approval of the rapid-response force by the 28-nation alliance, said it would send a clear message to potential aggressors.
"Should you even think of attacking one ally, you will be facing the whole alliance," he declared as a two-day NATO summit in southern Wales drew to a close.
However, Ukraine is not a full member of NATO but a "partner," which means it cooperates on a range of issues with the alliance, including receiving some military assistance. The partner status means that overt military intervention by NATO against Russia for its actions in Ukraine is extremely low because there is no enshrined commitment to do so.
Rasmussen said the quick-response force would give NATO a "continuous presence" in Eastern Europe, with alliance countries contributing forces on a rotational basis.
British troops will make up one-quarter of the force, which will be based initially in eastern Europe to ease the fears of the Baltic States of Latvia, Lithuania and Estonia, the new NATO members located near Russia, The Guardian reports.
Marshall Bradley Webb, a U.S. Air Force lieutenant general who currently serves as NATO's Special Operations Commander, a unit that will support NATO's ambitions to react more quickly to security threats, described NATO special operations as "the new kid on the block."
He said the unit is "rapidly deployable, agile" and can be activated "at a moment's notice." He spoke to journalists in Wales, where NATO was demonstrating its hybrid Osprey aircraft that can fly like a plane but land like a helicopter.
Rasmussen also said allied countries feel a new urgency to meet a long-sought goal of spending 2% of their GDP on defense and security.
"Russian aggression against Ukraine is a wake-up call," he said, adding that for NATO countries "it is now obvious that we cannot take our security for granted."
In addition to NATO's announcement, Western leaders were already prepared to impose additional sanctions on Russia if the peace talks fail.
Rasmussen earlier had expressed caution over the prospects for a genuine settlement in Ukraine, saying that in the past peace overtures from Russia have not lived up to their promise.
"We have seen similar statements and initiatives and they have been a smoke screen for continued Russian destabilization of the situation in Ukraine," Rasmussen said.
The United Nations estimates that more than 2,600 people have been killed since the conflict began in April. Washington and Europe have warned Russia that if the crisis in Ukraine continues it may face further sanctions.
On Thursday night, NATO leaders also discussed at a working dinner the threat posed by the militant group Islamic State. "Our message is clear: we are united in condemnation of these barbaric acts," Cameron said, referring to the beheading or two American journalists.
Doug Stanglin reported from McLean, Va.; Contributing: Associated Press