On Jan. 5, 18 people — mostly the children and wives of Russian diplomats — boarded buses and embarked on a 15-hour drive home to Moscow, according to a senior Ukrainian security official.

About 30 more followed in the next few days, from Kyiv and a consulate in Lviv, in western Ukraine. Diplomats at two other Russian consulates have been told to prepare to leave Ukraine, the security official said, speaking on the condition of anonymity to discuss national security matters.

How to interpret the evacuation has become part of the mystery of divining the next play by President Vladimir V. Putin of Russia. Thinning out the Russian Embassy may be part propaganda, part preparation for a looming conflict or part feint, Ukrainian and U.S. officials say. It could be all three.