Despite assurances from President Petro O. Poroshenko that the agreement would keep Ukraine whole, there was concern that Russia, after using its army to deal a military blow against Ukrainian troops, was dictating terms that would keep a significant portion of the country under its sway. It will largely be up to Mr. Poroshenko — who was elected in May on a platform of ending the war in two weeks and who faces parliamentary elections on Oct. 26 — to rapidly convince Ukrainians that negotiating with the separatists was their best choice.

“Ukrainian public opinion is not ready for a peace that does not reflect Ukrainian aspirations,” said Mykhailo Minakov, a professor at the University of Kiev-Mohyla Academy and a civil rights activist. “They are not ready to respect an agreement that would respond to the demands of the separatists or the Russians.”…

Many believe that he seeks to create a frozen conflict — much as Russia did in Georgia and Moldova — to keep Ukraine permanently destabilized with a breakaway region in its southeast corner. Since March, Moscow has demanded that Ukraine put in place a federal system that would give regions significant autonomy, including the ability to establish their own foreign policy.