Marjah, Afghanistan ? Armed with assault rifles and fistfuls of American dollars, government agents on Wednesday drove deep into Afghanistan’s biggest poppy-growing region to begin enforcing a plan to eradicate the opium-bearing crop.

As soldiers with Kalashnikov rifles and grenade launchers looked on, tractors chewed up fields of poppy in one part of Helmand province, which produces most of Afghanistan’s opium. Farmers said they had little choice but to accept state compensation money.

“They have gunmen, they have cars, they have force,” said Durjan, a 23-year-old farmer who planned to plant beans where poppies once stood. “We have no option.”

At the urging of the United Nations and foreign governments, the weak Afghan government is rushing to wipe out the crop that provides the raw material for heroin just two weeks before most farmers harvest the plant.

Afghanistan was once the source of 70 percent of the world’s opium. The Taliban successfully banned poppies in 2000, but farmers quickly planted them again as the U.S. bombing campaign helped push the Islamic militia from power late last year.

The government is paying poppy farmers $350 to destroy a jirib, an Afghan land measure equivalent to half an acre, said Shabaz Ahmedzai, an adviser to interim Prime Minister Hamid Karzai.

The amount is close to the $400 farmers say it costs them to plant a jirib, but still far less than the $1,700 they could expect to receive if they harvested the poppies.

Durjan said he expected to be paid $1,750 by the government for his five jiribs.

Flanked by an aide with two stacks of crisp $50 and $100 bills, Ahmedzai sat in a farmer’s guest house and doled out cash, note by note, to laborers who had complied with the eradication program.

He said the money had been provided by the United Nations, and urged foreign governments to provide more aid for schools, irrigation and other public projects to prevent more destitute farmers turning to illegal crops.

“If this doesn’t happen, we’ll face the same problem again next year,” he said.