BRUSSELS — World leaders on Wednesday waited to see if Russian President Vladimir Putin would cast the die and order troops deeper into Ukraine. At the same time, they worked to maintain a united stance and vowed to impose tougher sanctions in the event of a full-fledged invasion.
With Russian lawmakers having authorized Putin to use military force outside the country and Ukraine surrounded on three sides by more than 150,000 troops, the rumble of tanks did not appear far off.
The U.S. and key European allies accused Moscow of having already crossed a red line by formalizing a military deployment to regions of eastern Ukraine controlled by Russia-backed separatists. Ukrainian authorities, after weeks of trying to project calm, signaled increasing concern.
Here are the things to know about the conflict over Ukraine and the security crisis in Eastern Europe:
