Questions remain after Ukraine cease-fire deal announced

WATCH: Ukrainian and Russian leaders have agreed to a ceasefire to start Sunday. But as Eric Sorensen reports, there’s skepticism about whether Putin will honour his part of the deal.

MINSK, Belarus – The peace deal reached Thursday for Ukraine, if it holds, would be a partial win for both Moscow and Kiev: Ukraine retains the separatist eastern regions and regains control of its border with Russia, while Russia holds strong leverage to keep Ukraine from ever becoming part of NATO.

But neither side came away from the marathon talks unscathed.

There’s no sign Russia will soon escape the Western sanctions that have driven its economy down sharply, and Kiev’s price for regaining control of the border with Russia is to grant significant new power to the east.

But the complicated calculus of whether any side came out truly ahead can’t be determined unless a single, straightforward term is fulfilled: halting the shooting and artillery salvos that have killed more than 5,300 people since April. That is supposed to happen on Sunday, at one minute after midnight.

A cease-fire called in September never fully took hold and fighting escalated sharply in the past month. Questions remain about whether either side possesses the will or discipline to ensure a truce this time.

The cease-fire is to be monitored by the Organization for Security and Cooperation in Europe’s observer mission in Ukraine.

But that “will probably go nowhere if there isn’t a huge political will to beef up the OSCE, pull in many more monitors, give them clear support,” said analyst Judy Dempsey, an associate of the Carnegie Europe think-tank.

The OSCE mission head, Ertugrul Apakan, said Thursday that he expected it would expand by the end of the month to about 500 observers, up from about 310 currently, the Interfax news agency reported.

WATCH ABOVE: Shelling in east Ukraine prior to ceasefire announcement

Under the terms of the deal reached after 16 hours of talks between the presidents of Russia, Ukraine, Germany and France, the next step is to form a sizeable buffer zone between Ukrainian forces and Russia-backed rebels. Each side is to pull heavy weaponry back from the front line, creating a zone roughly 30-85 miles (50-140 kilometers) wide, depending on the weapon caliber.

READ MORE: White House voices support for Ukraine peace talks in Minsk

Then come the knotty and volatile political questions.

While Russian President Vladimir Putin told reporters the deal envisages special status for Ukraine’s separatist regions, Ukraine’s president, Petro Poroshenko, maintained there was no consensus on any sort of autonomy or federalization for eastern Ukraine.

In addition, the agreement foresees the regions being able to form their own police forces and to trade freely with Russia, both of which would bring a degree of division and uncertainty within Ukraine that could be leverage to keep the country out of NATO.

Those measures would require constitutional reform, certain to be a highly fraught process.

“Anything that has to go through the Ukrainian parliament has a huge question mark attached to it,” said Eugene Rumer of the Carnegie center. “It is going to be the subject of a huge and very fierce debate in Kiev.”

WATCH: Helping Ukrainians on the front lines. Kent Morrison reports.

Only after such reform is passed would Ukraine’s full control over its border with Russia be restored, according to the pact.

Aside from the political resolution of the east’s status, Ukraine also faces severe challenges with its troubled economy, which is close to bankruptcy. On Thursday, the International Monetary Fund agreed to give Ukraine a new bailout deal worth $17.5 billion (15.5 billion euros). The World Bank, meanwhile, announced it was ready to commit up to $2 billion to help Ukraine with reforms, to fight corruption and for other purposes.

Despite the uncertainties, the agreement’s initiators saw it as a step forward.

“We now have a glimmer of hope,” said German Chancellor Angela Merkel, who brokered the talks in the Belarusian capital of Minsk together with French President Francois Hollande.

“But the concrete steps, of course, have to be taken. And we will still face major obstacles. But, on balance, I can say what we have achieved gives significantly more hope than if we had achieved nothing.”

READ MORE: Fighting in Ukraine continues ahead of peace talks

As for Putin, he told reporters: “It was not the best night of my life.”

“But the morning, I think, is good, because we have managed to agree on the main things despite all the difficulties of the negotiations,” the Russian leader said.

Battles continued Thursday even as the talks went on, and Ukrainian military spokesman Andriy Lysenko said Russia sent 50 tanks and a dozen heavy weapons overnight into Ukraine.

In the rebel stronghold of Donetsk, residents who have seen their city pounded daily by artillery since late May were skeptical of the deal.

“We will see whether there will be a cease-fire or not,” said resident Tatyana Griedzheva. “You have seen it with your own eyes, the kind of cease-fire that we have already had.”

A previous cease-fire in September was violated repeatedly as Ukrainian forces and the rebels both tried to gain more ground.

Poroshenko stressed that the pact contains “a clear commitment to withdraw all foreign troops, all mercenaries from the territory of Ukraine,” a reference to the Russian soldiers and weapons that Ukraine and the West say Russia has sent into eastern Ukraine to back the rebels.

Moscow has denied the accusations, saying any Russian fighters were volunteers, but the sheer number of sophisticated heavy weapons in the rebels’ possession belies that.

Still, Merkel said, in the end, Putin exerted pressure on the separatists to get them to agree to the cease-fire.

“I have no illusions. We have no illusions. A great, great deal of work is still necessary. But there is a real chance to make things better,” she said.

In Brussels, European Union President Donald Tusk said the test of the Minsk agreement will be whether the weekend cease-fire holds in eastern Ukraine.

The French-German diplomatic offensive came as President Barack Obama considered sending U.S. lethal weapons to Ukraine, a move that European nations feared would only widen the hostilities.

“The true test of today’s accord will be in its full and unambiguous implementation, including the durable end of hostilities and the restoration of Ukrainian control over its border with Russia,” White House press secretary Josh Earnest said.

The urgency felt by all sides was underlined by the extraordinary length of the talks, which began Wednesday evening and continued uninterrupted through the night as crowds of reporters waited anxiously in a marble-floored, chandeliered convention hall in Minsk.

While the four leaders hailed the agreement, Russia and Ukraine still disagreed on how to end the fighting around Debaltseve, a key transport hub between the rebels’ two main cities of Donetsk and Luhansk.

Putin said the rebels consider the Ukrainian forces there surrounded and expect them to surrender, while Ukraine says its troops have not been blocked.