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President Obama said late Wednesday he hoped the just-announced Ukraine truce would "provide space for the sides to resolve their disagreements peacefully."

Speaking at the end of a news conference in Mexico with fellow North American leaders, he added that ultimately it was the government's responsibility "for making sure that we shift toward some sort of unity government, even if it's temporary, that allows us to move to fair and free elections so that the will of the Ukrainian people can be rightly expressed without the kinds of chaos we've seen on the streets, without the bloodshed that all of us, I think, strongly condemn."

Earlier Wednesday, he called for Ukraine’s military to refrain from using violence against its own people and said the United States would be watching how the Eastern European nation handled the lethal escalation in the country.

“I want to be very clear as we work through these next several days in Ukraine that we're going to be watching closely and we expect the Ukrainian government to show restraint, to not resort to violence in dealing with peaceful protestors,” the president said.

Obama’s comments come on the heels of Ukraine’s embattled president announcing he would replace the army chief Wednesday, and the military saying it would take part in a national anti-terrorist operation to restore order.

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    "There will be consequences if people step over the line," Obama said shortly after landing in Mexico for a summit with the leaders of Mexico and Canada. "And that includes making sure that the Ukrainian military does not step into what should be a set of issues that can be resolved by civilians."

    Russian President Vladimir Putin and his policies were at center stage as the world watched the bloody escalation of nearly three months of anti-government protests in the Ukraine – once a stronghold in the former Soviet Union – give way to a civil war.

    So far, 26 people have been killed in the country’s capital of Kiev and hundreds more have been injured or displaced.

    The bloodbath that began on Tuesday violently exposed the country’s deeply-divided loyalties between Russia and the West.

    Ukrainian President Viktor Yanukoyych blames opposition leaders for the violence while Russian authorities likened the situation to a coup.

    “I think it’s very hard to go back now and have any kind of negotiated outcome, but I have to say the power of the government may be enough to push the demonstrators out of Independence Square and impose pretty strict control,” former UN Ambassador John Bolton said Wednesday on FoxNews.com’s “Defcon3.”

    “The demonstrators themselves are divided, the opposition is divided… The president has the backing of Russia and Vladimir Putin, so unfortunately I think he definitely has the upper hand at the moment.”

    Bolton says the U.S. has mishandled the situation for too long and has decreased its options.

    “Where has Obama been on this? Absent without leave, that’s the only way you can describe it,” Bolton, a Fox News contributor, said.

    Among the most damaging missteps the West has made in terms of securing peace in the region “has been assuming that the (European Union) knew what to do and could stand up to Russian pressure,” Bolton said.

    On Thursday, the European Union will meet with its 28 member countries to address the escalating situation in the Ukraine. The leaders of Poland and France are expected to be in the Ukraine tomorrow.

    “I think this is a huge test of America’s will face with a very resolute Vladimir Putin, determined to impose his will,” Bolton said.  “The president’s still pressing that reset button back from 2009 …  I don’t understand it, the president’s from Illinois. Chicago has a large, large Ukrainian presence that you would think over the years as a senator that he would be sensitive to. And yet he’s simply not on the field.”

    On Wednesday, Sen. Marco Rubio, R-Fla., urged the Obama administration to “use every diplomatic means at its disposal, including sanctions, to bring accountability to those involved in acts of violence throughout Ukraine.”

    He’s also pushing for the Senate Foreign Relations Committee and Congress to move quickly to approve the Global Human Rights Act, which would strengthen the President's ability to impose these punishments.

    "Ukrainians have made clear that they want the opportunity to be governed free of corruption and Russian pressure,” Rubio said. “Ukraine's future lies in Europe, not Vladimir Putin's Russia. America stands with those who seek freedom even at great risk to their own security.”

    The Associated Press contributed to this report