Ukraine's foreign minister said a full withdrawal of Russian forces and heavy weapons is a precondition for a sustainable cease-fire with separatists.
Pavlo Klimkin told reporters at the United Nations in New York Monday that Russia has to show the political will for a lasting truce.
He also said closing the border between Ukraine and Russia and a deal on freeing hostages held by the separatists are key preconditions for a cease-fire.
Russia has consistently denied having soldiers inside Ukraine or arming the separatists.
Ukrainian officials said earlier they have started to pull troops from a buffer zone in the east of the country where they have been fighting pro-Russian separatists.
Security and Defense Council spokesman Colonel Andriy Lysenko said Monday rebel attacks have diminished, allowing Kyiv to implement an agreement reached last week with the separatists to create the 30-kilometer buffer.
On Sunday, Ukraine had said it would not pull its forces until cease-fire violations stopped, and that several violations had occurred.
Ukraine, buffer zone, Sept. 22, 2014
Ukraine will be high on the agenda this week at the U.N. General Assembly in New York. Russian President Vladimir Putin will not be in attendance. Instead, Foreign Minister Sergei Lavrov will represent Moscow at the annual meeting.
However, Kremlin officials say Putin will attend the G20 summit in Australia in November where the Ukraine conflict is expected to be a main topic of discussion.
Ukrainian President Petro Poroshenko told Ukrainian media Sunday that Kyiv cannot win back control of the east solely through military means. He said no matter how many Ukrainian forces are deployed, Russia will send in as many troops as needed to counter.
Costs for Russia
A former Russian finance minister said the Ukraine crisis will come at a high cost for Moscow over the next few years.
Projecting losses in the tens of billions of dollars every year for the near future, Alexei Kudrin said on Monday that the country will be pushed to the point of recession for at least three years.
According to Kudrin, sanctions which the West imposed on Moscow will account for a one percent reduction in Russia’s GDP, with the country facing additional costs that will be needed to prop up Crimea, which Russia annexed from Ukraine in March.
“Speaking about losses, one percent of the GDP growth is 700 billion roubles this year, so it's more than $20 billion lost just in GDP growth. And there will be more expenditures. Every year, spending on the Crimean territory will amount to about three billion dollars,” said Kudrin, talking to reporters in Moscow.
Compensation payments for the impact of sanctions on Russian companies and sinking world oil process will present additional hardships for Moscow, Kudrin added.
On Sunday, thousands of Russians marched in Moscow against what they and the West see as the Kremlin’s instigation and direct involvement in the conflict in Ukraine’s east.
Opposition leader and march organizer Boris Nemtsov said that the crisis in Ukraine is Putin’s revenge for Ukraine's revolution, which ousted the Moscow-backed "corrupt thief president [Viktor] Yanukovych” and put the country on a pro-Europe course.
One protester told VOA that Putin is dragging Russia into chaos, nationalism and fascism.
Counter-demonstrators who support the Kremlin called the marchers traitors. Scuffles broke out between both sides despite a heavy police presence.
Organizers of the march said over 50,000 people took to the streets in the Russian capital, but police claimed the number was exaggerated, putting it instead at 5,000.
Watch Moscow protest video report by Daniel Schearf:
Some material for this report came from Reuters.