A year ago this week, some pro-Russian demonstrators assaulted a government building, in Donetsk, Ukraine, taking control of two floors. Coming only weeks after the outright conquest and annexation of the Crimean Peninsula by President Vladimir Putin of Russia, it marked the beginning of a violent conflict that turned into part civil war, part clandestine Russian invasion of eastern Ukraine.
Mr. Putin has won this round, though the game continues. There's real apprehension that, having enjoyed success once, he may use the same game plan elsewhere, such as in the Baltic states. The past year has not been the West's finest moment: The failure to deter or punish Mr. Putin's aggression has left Ukraine in an extremely difficult position.
On Monday, Petro Poroshenko, the President of Ukraine, reluctantly and grudgingly accepted the holding of a referendum on "federalization." The proposal for some degree of decentralization for the regions of Donetsk and Luhansk in eastern Ukraine, where the ethnic Russian population is large, was a painful concession extracted for the cessation of the war between Ukraine, on the one hand, and the pro-Russian militants and thinly disguised Russian forces, on the other. On April 15, the constitutional reform committee of the Ukrainian parliament will start work on this matter.
The shaky peace agreed to in Minsk, Belarus, in February, included "decentralization of power, including through the adoption of the Ukrainian law 'On temporary order of local self-governance in particular districts of Donetsk and Luhansk oblasts' " – including a "right of language self-determination."
The constitutional amendment required by the Minsk agreement is supposed to be completed before the end of the year. In spite of the unjust circumstances in which Ukraine was induced to consent to decentralization in the east of the country, it would be rash for Kiev to renege now on the referendum. That would be to offer Mr. Putin an excuse to start the vicious cycle of violence all over again.
Ukraine doesn't need more appeasement. But it badly needs peace.