KIEV, Ukraine —Russian President Vladimir Putin backed Ukraine’s cease-fire plans Saturday and appealed to both sides to halt all military operations.

The Kremlin said in a statement that Putin “calls on the opposing sides to halt any military activities and sit down at the negotiating table.”

The statement said Putin supported Ukrainian President Petro Poroshenko’s decision to order Ukrainian troops to observe a unilateral cease-fire starting Friday night.

Poroshenko bills the weeklong cease-fire as the first step in a wider peace plan that would include an amnesty for pro-Russian separatist fighters.

Putin said however that without action directed at starting talks, the plan was “not viable and unrealistic.”

Ukrainian troops have struggled to suppress separatists who have seized buildings and declared independence in the eastern Donetsk and Lugansk regions near the border with Russia.

Ukraine and the United States have accused Russia of supporting the insurgency, including by permitting tanks to cross the border and wind up in the rebels’ arsenal.

Russia counters that it is not supporting the insurgents and Russians who have joined the fighting are doing so as private citizens.

It has been unclear whether Russia can or will influence the fighters to de-escalate the conflict. Putin consulted with Poroshenko several times by phone about the cease-fire, but Russia’s foreign minister earlier Saturday had criticized it sharply as an “ultimatum” to rebels.