In assessing Iraq's nuclear potential it's a mistake to focus exclusively on the expertise of Iraqi scientists and nuclear industry.

Saddam Hussein doesn't need to manufacture the plutonium and enriched uranium essential for the bomb. He could conceivably buy what he needs in a nuclear black market or simply steal it.He has tried in the past. In 1982, Iraqi officials tried to buy 75 pounds of French plutonium for $62.5 million from two arms dealers who promised but never produced the material.

Unfortunately, there can be no ironclad assurances that Iraq has not already succeeded in acquiring the nuclear explosives it needs to complete its weapons.

Inspections, such as the twice yearly visits of the International Atomic Energy Agency (IAEA), can't tell us anything about Iraq's clandestine activities.

These concerns about Iraq expose the central problem of the global non-proliferation system: Permitting the use of bomb-grade plutonium and uranium fuels in civilian nuclear power and research programs.

The undetected removal of just a tiny percentage of the tons of plutonium in an industrial state such as France, Germany, Belgium or Japan would represent a substantial amount of bomb material.

Large nuclear fuel plants in Europe and Japan extract and process tons of plutonium from spent reactor fuel every year. Because of inherent uncertainties in measuring large flows of plutonium, which is processed in liquid or powder form, officials are forced to estimate.

If the amount recovered from the fuel falls within a certain margin of error, it is assumed that all the bomb-grade material has been accounted for.

The IAEA does not come close to achieving its goal of detecting the loss of one bomb's worth of plutonium - 17 pounds - per plant per year.

A number of remedial steps should be taken. Extraordinary measures are needed to protect nuclear facilities against theft.

There should be more frequent IAEA visits to Iraq - once a week instead of twice a year - to correspond with the minimum time needed to convert the country's known stocks of nuclear fuel into pure uranium for a bomb.

The agency should also exercise its right to conduct special inspections in Iraq to seek out undeclared bomb material or finished weapons. And it should end its policy of keeping the details of its findings secret.

Finally, "peaceful" bomb-grade materials must be replaced with alternative fuels that cannot be turned into weapons.

This had been a high U.S. priority until the Reagan and Bush administrations decided that non-proliferation benefits were not worth the political costs of resisting European and Japanese appetites for plutonium and highly enriched uranium.

If there is to be any hope that future crises will be spared a nuclear dimension, the White House must reverse this "see-no-evil" policy.