Story highlights
NEW: Ukraine military reports first violation of the ceasefire, saying motar fire hit a post near Zolote
NEW: Ukraine's president warns separatists about Debaltseve, a strategically located railroad hub
President Petro Poroshenko declares ceasefire is in effect
After days of ferocious attacks, a ceasefire went into effect after midnight Sunday in Ukraine, followed by brief accusations of violence.
The separatist Donetsk People’s Republic also announced the ceasefire.
But less than 90 minutes after it started, Ukrainian officials reported mortar shelling at a military post near Zolote in the Luhansk region.
CNN teams in Ukraine said the shelling quieted shortly after midnight.
The peace agreement signed in Minsk, Belarus, several days ago comes with many questions over how it will be implemented and whether it will stick. Mistrust is high on both sides, adding to the doubts.
Debaltseve, a strategically located railroad hub in the East, is a crucial piece of the ceasefire.
In his speech announcing the ceasefire, Poroshenko said Ukrainian troops control the town and warned militants to stay away.
“I think the fact of using the tense situation on the outskirts of Debaltseve by militants-terrorists-mercenaries poses a great threat, which can violate the ceasefire regime,” Poroshenko said.
Separatists claimed to have encircled Debaltseve.
“Debaltseve will be a vital flashpoint for the hours ahead,” he said.
Poroshenko has warned that if the separatists do not abide by the ceasefire, he will impose martial law throughout Ukraine’s territory.
Poroshenko’s office said he spoke on the phone with German Chancellor Angela Merkel, French President Francois Hollande and U.S. President Barack Obama in the hours before the ceasefire was due to take effect.
Shelling hours before
Separatist militants who spoke to CNN voiced their anger against government forces, whom they blame for the deaths and devastation in their communities.
Shelling rocked two eastern Ukrainian cities Saturday ahead of the ceasefire, raising fears that the deal to end the bitter conflict might be in jeopardy.
Both incoming and outgoing artillery could be seen in the vicinity of the coastal city of Mariupol, and there was significant shelling in the city of Donetsk.
Ukraine’s National Defense and Security Council reported seven soldiers killed and 23 wounded in 24 hours. The council said additional forces were crossing the border from Russia into Ukraine in the area of Novoazovsk.
Igor Martinov, separatist-appointed mayor of Donetsk, said two people were killed and four injured by shelling in the city center Saturday afternoon.
Poroshenko said that after the agreement reached Thursday by the leaders of Ukraine, Russia, Germany and France, the offensive by the separatists had intensified.
The separatists may be trying to take control of strategic locations, such as the railroad hub of Debaltseve to the north, before the ceasefire lines are drawn. Pro-Kiev militia have also been pushing forward around government-controlled Mariupol.
As the shells rain down, the toll on eastern Ukraine’s residents only grows.
The Ukrainian military operation against the separatists said Friday that 14 civilians had been killed by rebel shelling, six in the village of Shchastya, five in the village of Hornyak and three in Artemivsk, according to the official Ukrinform news agency.
Each side has accused the other of shelling civilian areas in the course of a conflict that has killed more than 5,000 people.
OSCE urges reduction of hostilities
Under the deal, both sides were expected to start pulling back their heavy weapons from the front lines Monday, creating a buffer zone at least 50 kilometers (31 miles) wide.
The OSCE has the challenging task of overseeing the process.
“We need to have an effective ceasefire,” OSCE Secretary General Lamberto Zannier said Friday. “So I’m already concerned that we are seeing this morning a continuation of hostilities.”
The OSCE hopes to see a reduction in hostilities between now and Saturday night, he said.
“I would expect the ceasefire to stop (armed) operations and to stop people where they are,” he said.
While Ukrainian forces have to pull back their heavy weapons from the front line as they stood Saturday night, separatist forces must pull back theirs from the front line as it was on September 19, when a previous peace agreement was signed in Minsk. That swiftly disintegrated amid continued violence.
It also envisions prisoner swaps, new local elections in the conflict-affected regions of Luhansk and Donetsk, and a law granting amnesty to those involved in the fighting.
However, Svyatoslav Tsegolko, a spokesman for the Ukrainian president, said that those responsible for shooting down Malaysia Airlines Flight 17 over Ukraine last summer will not be given amnesty under the Minsk agreement.
This could be a potential obstacle to keeping the separatists on board.
Western governments believe rebels used a Russian-supplied missile system to shoot down the jet after mistaking it for a military aircraft, while Kiev says it was a Russian officer who pressed the button. The separatists and Russia have denied any responsibility.
U.S. envoy: Separatists have more arms than some NATO states
The Kremlin has said it hopes to see the latest peace plan succeed, but reiterated Russia “is not a participant” in the conflict.
But Kremlin spokesman Dmitry Peskov told Russia’s state-run RIA Novosti on Friday that while Russia had helped to bring about the Minsk agreement, it wasn’t in its power to fulfill it “because Russia is not a participant in the conflict.”
Russia has steadfastly denied accusations by Kiev and the West that it is sending forces and heavy weapons into Ukraine.
But Kiev has accused it of continuing to do so even after the peace plan was signed in Minsk.
Geoffrey Pyatt, the U.S. ambassador to Ukraine, tweeted that the separatists “now have larger fighting force with more tanks armored vehicles, heavy artillery & rocket systems than some NATO and European countries.”
He also posted satellite images which he claimed show “Russian military, not separatist, systems” deployed in eastern Ukraine.
The United States has not ruled out providing “lethal defensive aid” to the Ukrainian military to help it defend against advances by the Russian-backed separatists.
Ukrainian forces have just received a delivery of lightly armored military vehicles from Britain, but that country’s Ministry of Defence said the vehicles were delivered as part of a commercial contract signed by a private company in 2013, before the conflict started.
CNN’s Frederik Pleitgen reported from Mariupol and Laura Smith-Spark wrote from London. CNN’s Ingrid Formanek and Nick Paton Walsh in Donetsk, Brian Walker, Alla Eshchenko and Claudia Rebaza contributed to this report, as did journalists Victoria Butenko and Azad Safarov.