U.S. intelligence agencies believe any smallpox samples Iraq possesses came from the last domestic outbreak of the deadly disease in the 1970s, rather than from rogue Russian scientists or other external sources, U.S. officials said.
Iraq is not believed capable of using smallpox as a weapon, and probably has only small amounts of the virus, the officials said. Indeed, U.N. inspectors, before leaving Iraq in 1998, made little mention of smallpox as a threat from Iraq.
Only the United States and Russia overtly possess samples of the deadly virus. The U.S. sample is at a government lab in Atlanta; the Russian sample is in Novosibirsk in Siberia.
But a recent U.S. intelligence assessment concluded that Russia probably has covert stockpiles of the virus, beyond its publicly known sample, U.S. officials have said, speaking on the condition of anonymity.
Officials also acknowledged the CIA is investigating reports that a Russian scientist covertly supplied Iraq with samples of the virus that had been enhanced to make a weapon. Officials said they have been unable to verify any of those reports.
The U.S. intelligence assessment also concluded that North Korea and France possess small but hidden quantities of the smallpox virus.
Like Iraq, North Korea is not believed to be able to use smallpox as a weapon.
France has denied having any samples of the virus. U.S. intelligence agencies believe any French quantities are for defensive research programs aimed at limiting casualties from a smallpox outbreak, U.S. officials said.
Fears that smallpox, declared eradicated in 1980, could be used as a weapon led the Bush administration to announce Friday it would offer vaccinations to the American public, probably beginning in 2004. The disease kills about a third of its victims.
U.S. officials worry that Iraq and North Korea could develop biological weapons with their samples, and that lax security could allow the Russian stockpiles to fall into others' hands. Some reports suggest Russia supplied North Korea with smallpox for weapons.
Ken Alibek, a former top scientist in the Soviet biological weapons program who came to the United States in 1992, claimed the Soviets covertly developed smallpox as a weapon in the 1980s.
Before 1998, U.N. weapons inspectors discovered limited evidence of a smallpox program in Iraq. They found a machine labeled "smallpox" and revealed that Iraq is experimenting with a related virus that infects camels. But their 1999 report on Iraq's weapons programs does not describe any smallpox weapons.
Al-Qaida is also believed to have sought samples of smallpox for weaponization, but U.S. officials don't believe the terror network is capable of mounting an attack with the disease. Evidence recovered in Afghanistan pointed to Osama bin Laden's interest in the virus, officials said.
Over the years, there have been reports that Libya, Syria and Iran also have smallpox samples, but U.S. officials believe that likelihood is low.
Routine smallpox vaccinations ended in the United States in 1972. Experts say those last vaccinated more than three decades ago have little residual immunity. But new vaccinations could also kill a small number of the people who receive them.