"We know that one thing is a declaration, another thing is implementation," he said. "Nevertheless, I would welcome, of course, if the new announcement of the cease-fire represents a sincere attempt to stop the violence and initiation of a constructive political process."
"The only reason that we're seeing this cease-fire at this moment is because of the sanctions already applied and the threat of further sanctions," Obama said.
Still, he suggested that if Russia de-escalates the conflict, the West could roll back sanctions.
In addition to the new measures, NATO leaders also began to reveal the details of a new Readiness Action Plan, which they say will increase NATO's visibility in Eastern and Central Europe, as well as improve the alliance's ability to react quickly to conflicts -- like the one in Ukraine. British Prime Minster David Cameron, the summit host, said Friday that Britain would contribute 3,500 personnel.
"We must increase our capacity," he said.
The show of support for Ukraine was finalized Thursday, officials said, in a small group meeting of Obama, European leaders and Ukraine’s President Petro Poroshenko, as well as a wider conference.
NATO leaders there agreed on a strategy for funneling security aid, such as weapons and body armor, as well as humanitarian assistance to Poroshenko's young, besieged government. Most of the aid will continue to come from individual member nations, but NATO will act as a clearinghouse, said Doug Lute, the U.S. ambassador to NATO.
Ukraine is not a NATO member but has partnered with the alliance in various missions, Lute noted. NATO will use that partnership “to continue to build the capacity of Ukrainian forces not for the purposes of working together in Afghanistan and Kosovo now, but actually for the purpose -- the fundamental purpose of defending their own country,” he said.
The NATO assistance is to be paired with new sanctions likely to be announced by the
White House officials suggested that the next steps would take a bigger bite at those sectors.