President Clinton will deliver a speech tomorrow on the need to prepare for conflict with Iraq. The main reason for possible action cited by U.S. officials is Iraq's stockpile of biological and chemical weapons. But how significant a threat does Saddam Hussein's country really pose? Following a background report, Jim Lehrer gets two experts' opinions.

JIM LEHRER; The threat posed by Iraq's weapons of mass destruction. Phil Ponce begins with some background.

PHIL PONCE: Last fall chief United Nations weapons inspector Richard Butler presented a report to the U.N. Security Council describing what was still believed to be in Iraq's military arsenal. UNSCOM, the United Nations special commission, reported that Saddam Hussein possessed more than 2,000 gallons of the deadly bacteria anthrax--even a small amount of which can kill thousands.

He also had 31,000 chemical warfare weapons and more than 600 tons of material to produce a deadly VX nerve agent. The report also said inspectors were unable to document the whereabouts of 4,000 tons of chemicals that could be used to produce weapons.

Nor could UNSCOM verify Iraqi claims it had destroyed delivery systems, such as Scuds, airframes and warheads. A former U.N. weapons inspector gave one example of the vastness of the Iraqi arsenal that survived the Gulf War to Correspondent Betty Ann Bowser.

DAVID KAYE, Former Chief Nuclear Weapons Inspector: Probably easiest to describe it visually and in dollar terms. In chemical weapons the major chemical weapons storage site is an area larger than the District of Columbia, and as far as you could look, all you could see is chemical weapons laying on the ground in bunkers, leaking. It was the most astounding site I've ever seen in the world.

BETTY ANN BOWSER: And do you have every reason to believe that there are even more sites than that today?

DAVID KAYE: I think I have every reason to believe that we have not found all of the weapons and all of the material.

PHIL PONCE: That site was destroyed by UNSCOM. But inspectors believe they still haven't found everything the Iraqi government may be hiding. That's because they've been denied access to some government buildings and compounds.

Here's what inspectors have been able to find and destroy so far: thirty-eight thousand chemical weapons, four hundred eighty thousand liters of chemical agents, forty-eight missiles, thirty special missile warheads for chemical and biological weapons, and hundreds of components used in chemical weapons production, an arsenal believed capable of killing every person in the world several times over.

Last week, United States National Security Adviser Sandy Berger said the threat from Iraq continues.

SAMUEL BERGER, National Security Adviser: Stockpiles of chemical and biological munitions and a small force of Scud-type missiles remain unaccounted for. And most importantly, Iraq still has the capacity to rebuild its production program for biological and chemical weapons and the missiles to deliver them.

As UNSCOM has come closer and closer to ferreting out Iraq's remaining weapons capacity, Saddam has become increasingly determined in his efforts to block the inspectors and end the inspection regime.

PHIL PONCE: Hours later, after watching the speech on CNN in Baghdad, an Iraqi spokesman rejected those accusations.

IRAQI SPOKESMAN: If they have any hint that Iraqi has developed a new weapon, why don't they put this in front of the Security Council, instead of speaking in front of the cameras and to the press? They can put it on the desk of the Security Council, and let them discuss it with UNSCOM people. It's nonsense.

PHIL PONCE: Whatever officials say in Baghdad in Washington, the countries in the Gulf region and Mideast continue preparations for a potential Iraqi strike with deadly weapons.