In the short term, at least, that's the dismaying expectation of a wide range of counterinsurgency and Afghanistan experts if President Obama authorizes McChrystal, the top commander in Afghanistan, to implement a wide-ranging counterinsurgency campaign with as many as 40,000 additional U.S. troops. Pentagon and White House officials say that decision will be made within weeks.

The United States is likely to be badly bruised in the coming months no matter what strategy it adopts in Afghanistan, according to military and civilian experts, many of whom asked to remain anonymous because of the political sensitivity of the current strategic review. But between the extremes of making no change in war strategy, and cutting back troops and other resources, the McChrystal plan is said to entail the fewest -- but still significant -- dangers.

Most public attention has focused on the pending request by McChrystal for troop reinforcements. But more significant than the troop numbers is his blueprint for a radical shift in the way the United States and its allies intend to fight the war.

Key among his proposed changes: rather than trying to fight everywhere, shifting forces to "critical areas,'' where the Afghan population is most at risk. Another key change: getting American troops -- and increasing numbers of U.S. civilians -- out of their armored vehicles and fortified bases into Afghan communities, and getting them to shuck body armor and helmets and to walk among the population unprotected, like the Afghans themselves do.

"Once the risk is shared, effective force protection will come from the people,'' McChrystal wrote in the strategy proposal now under consideration at the White House. "Accepting some risk in the short term will ultimately save lives in the long run.''

But as the overworked yet accurate phrase in vogue at the Pentagon has it, "the enemy gets a vote.'' And this particular enemy, as the Jihadist fighters in Iraq and Afghanistan have shown, is highly adaptive, quick to learn to blunt the impact of American precision weapons and to emasculate the U.S. doctrine for mass conventional warfare. Cheap IEDs, for instance, have demolished the U.S. advantage in armored vehicles, field commanders say.

McChrystal and his top aides, together with a dozen counterinsurgency experts, put together the 66-page proposal for a new counterinsurgency strategy this summer – and then set up an aggressive "Red Team'' to play the Taliban, looking for weaknesses and vulnerabilities. Satisfied that he knew the risks and found them acceptable, McChrystal sent the proposal on to Defense Secretary Robert M. Gates and the White House.

Yet, the public may feel differently about the risks, especially in the short term. And that gives the Afghan insurgents a pressing motive to surge American casualties, to mount spectacularly bloody attacks, to impress on the American and European public the high cost of the campaign, analysts say.

"Nobody I know thinks this war can be won in a year or two years,'' said Stephen Biddle, a senior analyst for the Council on Foreign Relations and a member of McChrystal's strategy brain trust. "You could certainly lose political support for the war in the U.S. much sooner than that.''

Politically savvy insurgents are familiar with that timeline. And, because it would take a year to get U.S. reinforcements in position, the 68,000 American troops now in Afghanistan will be at risk. The Taliban will respond with "a cheap campaign of IEDs, mortars and rocket and mortar attacks'' on clusters of U.S. troops, said T.X. Hammes, a retired Marine colonel and counterinsurgency expert. Others expect the Taliban to deepen their infiltration of the Afghan army and national police force; already, insurgents have been discovered with Afghan police uniforms and vehicles. "You have one of them 'go postal' and kill an American – that just poisons the relationship between our military and their security forces,'' said David Isby, a Washington-based defense expert and author of several books on Afghanistan.

Experts also express worry that the insurgents yet could find a supply of shoulder-launched anti-aircraft missiles, perhaps from Iran, to use against troop-carrying cargo planes and helicopters, the lifeline of U.S. forces in the country.

Under the McChrystal campaign plan, some regions of Afghanistan would be left sparsely defended if at all, opening new opportunities for Taliban propaganda victories. Some senior U.S. military officers are worried about how to blunt powerful Taliban messages that would say, in effect, "Look, we forced the powerful Americans out and they have abandoned you, just like they abandoned Afghanistan before.'' There is concern as well about reprisal killings of Afghan police and others who cooperated with U.S. forces before they were withdrawn.

A Taliban "surge'' across large swaths of undefended rural Afghanistan would mirror the strategy they used in the mid-1990s in their successful sweep to power, building bases of support from one village and rural district to another while rival Afghan militias tried to defend large towns and cities. That strategy was "innovative and ruthlessly effective,'' Seth G. Jones of Georgetown University writes in a new book about the Afghan war, In the Graveyard of Empires.

"Afghanistan is fundamentally about legitimacy, and having the Taliban set up liberated zones would be huge,'' said Isby.

The largest Afghan insurgent group, the Quetta Shura Taliban, already has set up shadow governments in most Afghan provinces, complete with grievance boards, courts, tax levies and military conscription. U.S. officials say they have only a superficial knowledge of the depth and breadth of these networks.

Senior military officers also expressed concern that insurgents might use existing shadow networks in the major southern city of Kandahar or even in the capital, Kabul, to stage a spectacular attack similar to the 1968 Tet offensive. That was a surprising but largely bungled series of attacks across South Vietnam by Viet Cong insurgents. Although the insurgents suffered huge losses, scenes of fighting inside the U.S. embassy in Saigon and elsewhere shocked the American public and helped turn opinion against the war.

Even short of such drama, the costs of any Afghan war strategy, "to have any reasonable chance of success, are going to be high,'' said Biddle. He and others believe it will require a major effort by Obama and European leaders to convince the public on the necessity of accepting high up-front costs. "I suspect it will probably require a very systematic, deliberate attempt by the executive branch to make the case to the public'' he said, "that on balance, the costs are worth paying.''