Tensions escalated in eastern Ukraine on Wednesday, with pro-Russian gunmen storming City Hall in the sprawling city of Donetsk and a cluster of Ukrainian troops meant to be restoring order in the region apparently defecting to the side of separatists. The events suggested the challenge ahead for the pro-Western Ukrainian government on the second day of a campaign to quell the restive east, and came as Russian President Vladimir Putin warned that Ukraine was on the verge “of a civil war.”
