Worried about a vast and still growing heroin industry in Afghanistan, the Bush administration has devised a more aggressive counternarcotics strategy aimed at greater eradication of poppy fields, promotion of alternative crops and prosecution of traffickers.

The plan, a mix of stronger carrots and sticks, attempts to bring more coordination, more money and more muscle to Afghan and international programs launched over the past three years that have not made much of a dent in the lucrative drug business.

The intensified campaign stops short of using U.S. troops to target opium labs and attack drug kingpins. Instead, at the Pentagon's insistence, U.S. forces will be limited to supporting Afghan law enforcement efforts by providing airlift and intelligence leads to Afghan police and by helping tighten security along Afghanistan's borders, administration officials said.

The new approach emerged from a high-level administration review this summer of U.S. operations in Afghanistan. The review acknowledged the gravity of the drug problem and the ineffectiveness of past measures to confront it, according to several officials who participated.

President Bush is scheduled to be briefed this week on the revised U.S. strategy, which his principal national security advisers approved in outline form in mid-September. To fund it, officials expect to notify Congress soon of plans to shift more than $700 million from other programs into Afghan counternarcotics activities in 2005. That compares with about $123 million spent by the Pentagon and State Department in 2004.

"The issue in Afghanistan, I think from my viewpoint, is the drug issue. . . . That's the next big challenge in Afghanistan," Air Force Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, told a meeting of the Institute of Land Warfare earlier this month.

In an impoverished country with an average per capita income of less than $200 a year, the cash lure of the poppy plant is hard to resist. Afghanistan ranks as the world's largest producer of heroin, with more than 450 square miles of poppies under cultivation -- an area about the size of Los Angeles.

The country's earnings from the opium trade, estimated last year to exceed $2.3 billion, amount to more than half of Afghanistan's legal gross domestic product. Assessments of this year's crop by the CIA and the United Nations are due soon and will show a jump to record levels, officials said.

Most of the opium produced by Afghanistan goes to Europe, not the United States, feeding 95 percent of Europe's heroin demand. But the drug business has become a critical strategic concern for U.S. authorities because it helps finance the activities of insurgents and regional warlords. U.S. and Afghan officials now frequently cite the danger of Afghanistan becoming a "narco state," with drug-related corruption threatening to undermine the country's fledging democratic institutions.

Given the scope and urgency of the problem, some in the administration, in Congress and elsewhere have argued for direct U.S. military action against traffickers. They say Afghan forces are not yet large or strong enough to manage enforcement actions alone or ensure security for aerial spraying and other eradication efforts.

"Short-term, in order to eradicate the poppy and eliminate the income for those shooting at American soldiers, the U.S. military is going to have to provide protection to those doing eradication," said Rep. Mark Edward Souder (R-Ind.), who chairs a Government Reform subcommittee on drug policy. "There is no other option."

But U.S. commanders and senior Pentagon civilians contend that battling the drug trade is primarily a law enforcement problem, not a military one, and must be led by homegrown Afghan forces. Enmeshing U.S. troops in drug fights, they say, would alienate many Afghans -- some of whom have become useful intelligence sources -- and also divert attention from the core U.S. military missions of combating insurgents and aiding reconstruction.

"The last thing we want to do is have U.S. forces running around the countryside doing this sort of thing," said Col. David Lamm, chief of staff for the U.S. military command in Afghanistan. "That would change our relationship with the Afghan people, which right now is very positive."

Pentagon guidance allows U.S. troops in Afghanistan to destroy drugs they come across in the course of combat operations against al Qaeda and Taliban fighters. But senior defense officials resisted a proposal earlier this year that would have designated counternarcotics a core military mission in Afghanistan.

"The key to success there is not turning this into a military mission for the Americans," Douglas J. Feith, the Pentagon's chief policy official, said in an interview. "It's the Afghan government trying to enforce its own laws, and what we're interested in doing is building up their capacity so they could do it."

At the same time, Feith said, U.S. troops, who number about 15,000 in Afghanistan, will "be substantially more involved" in countering the drug trade. "There certainly is a sense this is a problem that we need to address because it could get to the point where it could endanger key goals of ours in Afghanistan," he said.

Lt. Gen. David Barno, the senior military commander in Afghanistan, has proposed expanding U.S. military counternarcotics assistance in three ways: by focusing more intelligence-gathering assets on suspected drug operations; by ferrying Afghan counternarcotics police in U.S. military aircraft; and by providing emergency support.

Two other broader security initiatives put forward by Barno would also enhance the country's ability to go after traffickers, defense officials said. One is a plan to strengthen key border checkpoints with more forces and equipment. The other would enlist U.S. troops in extended and specialized training of Afghan police.

After the U.S. invasion of Afghanistan in late 2001 and the fall of the Taliban government, Britain agreed to take the lead on counternarcotics -- part of an international nation-building plan that also gave the Germans the lead on police and the Italians the lead on courts. But some British strategies have faltered badly.

A plan in 2002 to compensate farmers who destroyed their poppy crops ended up spurring poppy cultivation. A 2003 effort to rely on local governors to eradicate poppy fields was misused for political purposes.

Reflecting concern in Washington about Britain's leadership on the issue, Souder's House subcommittee held a hearing in April with the unusually pointed title: "Are the British Counternarcotics Efforts Going Wobbly?"

The new U.S. approach, administration officials said, has been developed in coordination with the British and with Afghan President Hamid Karzai, who made clear publicly this month that going after traffickers would be a top priority of his newly elected government.

The U.S. plan calls for eradicating an area five to seven times larger than the nearly 10,000 acres of poppy fields destroyed this year. The destruction is to be offset by more than $100 million in aid to Afghan farmers to plant wheat, barley, corn and other crops and for other rural economic development projects.

A special Afghan interdiction force, trained by the British, and other Afghan counternarcotics police units will be expanded. Additionally, a special task force of prosecutors and judges to handle drug cases is being set up and will be housed in a secure facility -- a refurbished wing of the Pol-e-Charki prison on the outskirts of Kabul.

Another element of the plan includes the launching of a public awareness campaign to stress to farmers and other Afghans that the drug business poses a serious menace to the country and will not be tolerated.

Although Pentagon officials do not foresee any increase in U.S. troop levels in Afghanistan to support the new strategy, the U.S. Drug Enforcement Administration plans to increase its ranks in the country from eight agents and analysts to as many as 30, according to Doug Wankel, a former DEA agent who now serves as the counternarcotics coordinator at the U.S. Embassy in Kabul.

"We have to make an impact in the next year," Wankel said in a phone interview last week. "And I would say, in the next two years, we have to show this pendulum swinging back in the other direction or we run a real risk of losing Afghanistan."

Others warn, however, against expecting a quick solution or taking precipitous action that fails to cushion stronger eradication and interdiction measures with a substantial infusion of rural economic aid.

"Given the scope of the problem, it is not one that will get solved in one year," Lamm said in a phone interview. "We need to take a very deliberate, systematic and long-range approach to the problem or else we run the risk in many provinces of destabilizing the country."