BAGHDAD, Iraq (AP) _ The military instructor stabbed the dummy in the heart with a commando knife, and snapped at a group of Iraqi Popular Army recruits: ''This is your weapon to kill.''

One by one, the men dressed in camouflage fatigues lined up and stabbed the dummy in what was supposed to be hand-to-hand combat training at a suburban Baghdad soccer ground.

After Iraq's million-member regular army, these men and women are Saddam Hussein's second line of defense in the confrontation with the U.S.-dominated multinational force.

Every day, the Iraqi authorities organize marches through Baghdad and other cities by Popular Army recruits, among them elderly, gray-haired men and gun- toting women, some with heads covered by scarves in the Islamic tradition.

Teen-age boys clutch rocket-propelled grenade launchers and chant: ''Down, Down, Bush 3/8''

Iraqi officials boast that 8 million men and women have volunteered for the Popular Army in a wave of patriotic fervor supposedly sparked by Saddam's Aug. 2 invasion of Kuwait.

But Western and Asian military experts in Iraq estimate that the force's strength is probably closer to 600,000 personnel, a 25 percent increase over its pre-invasion numbers.

''We train on all weapons, but the emphasis is on close-combat weapons and hand-to-hand fighting,'' said Abdul Amin Jamil, one of the instructors.

''My son's in the army and I'm getting trained so that I can fight alongside him,'' said 51-year-old Karim Ali, holding an AK-47 assault rifle in one hand and patting a dagger hanging from his webbing belt.

''I may be needed to defend my country,'' said Fersan Hamid, a 15-year-old schoolboy. ''I'm willing to go to Kuwait and fight.''

Officials claim the volunteers reported to be flocking to join the militia include Palestinians, Egyptians, Syrians, Sudanese and other Arabs.

State TV regularly shows zealous recruits chanting undying allegiance to Saddam and military officials handing out guns to young and old to defend the republic.

Diplomats question how far the average Iraqi is prepared to go to defend a government as repressive as Saddam's. Still, the Popular Army is everywhere, guarding banks, embassies, hotels and government buildings.

With the prospect of war looming, the militia is reported to have been deployed in some numbers across Kuwait, occupying abandoned homes and government buildings.

Popular Army cadres are trained for two months - two hours a day, five days a week - in light weapons, anti-tank weapons and anti-aircraft guns.

After training, each recruit is given a firearm and allowed to keep it. They are required to report to their bases every week to determine if they're needed for active duty.

The militia was initially formed by Saddam in 1970 as the paramilitary wing of the ruling Baath Arab Socialist Party. Its main function was to act as an ideological counterweight to the army to prevent any attempt at a military coup.

Led by one of Saddam's closest associates, Deputy Prime Minister Taha Yassin Ramadan, the well-armed militia has been responsible for guarding the political leadership.

From an original strength of around 3,000, the Popular Army swelled to around 450,000, including 40,000 women, during the 1980-88 Iran-Iraq war. It was deployed at the front and suffered heavy casualties. Some 10,000 men were captured.

During the Iran-Iraq war, the Iraqi regular forces often resented having the less experienced militiamen deployed alongside them.

Western diplomats and Western military experts still doubt the Popular Army's fighting abilities, but some Asian diplomats believe that the Popular Army cadres could put up a fight if necessary.