Foreign Affairs; Now a Word From X – The New York Times

Thomas Friedman Op-Ed column on interview with George Kennan, architect of America's successful containment of Soviet Union; quotes 94-year-old Kennan's warning that NATO expansion is bound to draw adverse Russian reaction, and Kennan's criticism of Senate's superficial, ill-informed debate on such an important question; predicts future historians will surely remark on utter poverty of imagination that characterized US foreign policy at end of 1990's (M)