In a dramatic worsening of tensions in the restive east, three pro-Moscow separatists were killed in an overnight gunbattle with Ukrainian troops in the southeastern port city of Mariupol.
The violence highlighted the urgency of the talks, which bring together the foreign ministers of Russia, the United States, the European Union and Ukraine, as scores of pro-Kremlin separatists Kiev says are backed by Moscow have taken over parts of the former Soviet republic's southeast.
"Only through dialogue, through democratic procedures and not with the use of armed forces, tanks and planes can order be imposed in the country," Putin said from Russia in televised comments timed to coincide with the start of talks.
"I hope that they (participants in talks) manage to understand towards what abyss the Kiev authorities are going, dragging with them the whole country."
NATO promptly announced it was deploying more forces in eastern Europe and urged Russia to stop "destabilising" Ukraine, which has been in turmoil since the ouster of pro-Kremlin president Viktor Yanukovych in February and now threatens to split between its EU-leaning west and Russian-speaking east.