"The situation on the ground is very difficult and tense despite a declared ceasefire. We still have many shells thrown by terrorists  in eastern Ukraine,” Klimkin told reporters in Tokyo.
"There was always a problem of lack of trust in relations between Ukraine and Russia... we can't rely on any kinds of agreements between us and  Russians.
"And exactly because of that we need (a) consistent position of the whole international community for defending Ukraine peace and Ukrainian territorial sovereignty and territorial integrity."
Klimkin -- who is in Japan for meetings with Prime Minister Shinzo Abe and his counterpart Fumio Kishida – made the comments a day after the US and Russian foreign ministers John Kerry and Sergei Lavrov expressed cautious optimism following talks in Geneva.
Their meeting was part of efforts to end the fighting in Ukraine, where the UN says more than 6,000 people have died in less than a year.
Kerry and Lavrov both said a February 15 ceasefire was on the right track, despite repeated breaches.
Ukraine's army said Monday that one soldier had been killed but the ceasefire was still broadly holding.
Both sides have begun to pull back some heavy weaponry from the frontline, but monitors from the Organisation for Security and Cooperation in Europe have said it is too early to confirm a full pullback.
"What we need is, of course, at least a minor confidence and it could be provided by stopping any kind of shelling... and clear monitoring and verification by the OSCE monitoring mission," Klimkin said on Tuesday.
"We've been working on an additional stabilisation component -- it could be a UN mission, it could be a EU mission or (both) of them."
Klimkin is meeting Abe and Kishida to discuss a range of issues including Tokyo's support for Kiev over the crisis and strengthening economic ties.

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