The siege

摘要

Thank goodness for Petro Poroshenko. That is the response of some Western observers to the advances made by the Ukrainian army in its fitful war with Russian-backed separatists. Mr Poroshenko won the presidency in May on a promise to defeat the insurgents; his forces' victories this week have begun to fufil it. They have also persuaded some outsiders that Vladimir Putin has relinquished his bid to control or conquer eastern Ukraine-and that happily the West need harry him no further. That is a delusional and dangerous mistake.