Is it ensure, insure, or assure?
1660s, Cremelena, from Old Russian kremlinu, later kremlin (1796), from kreml' "citadel, fortress," perhaps of Tartar origin. Originally the citadel of any Russian city, now especially the one in Moscow. Used metonymically for "government of the U.S.S.R." from 1933. The modern form of the word in English might be via French.