Government Report Says 3 Nations Hide Stocks of Smallpox

Government officials say secret Federal intelligence assessment late last year concluded that Iraq, North Korea and Russia are probably concealing deadly smallpox virus for military use, and that this was important factor in Pres Clinton's recent decision to reverse course and forgo destruction of American stocks of virus; say evidence included disclosures by senior Soviet defector, blood samples from North Korean soldiers showing smallpox vaccinations, and fairly recent manufacture of smallpox vaccine by Iraq; besides United States, only Russia retains openly declared stocks of virus now, 20 years after disease was declared to be eradicated; intelligence assessment concludes Russia is hiding additional stocks of virus at military sites; American experts have clashed bitterly in recent years over whether virus exists outside two official repositories, in Russia and in United States (M)