True to form, Russian President Boris Yeltsin has astounded his country and the world. Demonstrating that nothing is more important to the mercurial Russian leader than the fate of his regime and his family -- it is hard to distinguish the two -- Mr. Yeltsin this week dismissed Prime Minister Sergei Stepashin and replaced him with Mr. Vladimir Putin, head of the internal security services. The move was unexpected, and remains unexplained; the only hint of a rationale is Mr. Yeltsin's statement that the new prime minister "is able to consolidate society" and continue reforms. History suggests the proper emphasis belongs on the first reason, not the second.

Mr. Putin is Russia's fifth prime minister in 17 months. He is even more unknown than his predecessor, Mr. Stepashin, who was plucked from relative obscurity only three months ago by Mr. Yeltsin. Being unknown need not be a disqualification. Mr. Stepashin has done a creditable job during his term in office. He seems to have put relations with the United States and the West back on track after the diplomatic dust up over Kosovo. During his recent trip to the U.S., he persuaded the International Monetary Fund to release another $4.5 billion in funds for the troubled Russian economy. His popularity within Russia seemed to be on the rise.

Mr. Stepashin may not have been the man Mr. Yeltsin wanted him to be, but his performance as prime minister has not warranted his dismissal (Indeed, in his first statement, Mr. Putin said that he would make few Cabinet changes and would continue his predecessor's policies.). But Russia's prime minister wears a second hat -- protector of the Yeltsin family interests -- and in this endeavor, Mr. Stepashin was falling short. The key evidence is the emergence last week of a new political alliance, the Fatherland-All Russia, launched by Moscow Mayor Yuri Luzhkov and his allies, several regional governors.