The Pentagon has made clear that the U.S. will leave Afghanistan when the rag-tag（由乌合之众组成的、混杂的） Afghan security forces have been beefed up to the point where they can keep the peace without help. "Significantly expanding [Afghanistan's national security forces] is, in fact, our exit strategy," Defense Secretary Robert Gates told U.S. troops in Kandahar last week. But that's a strategy that could leave U.S. forces in Afghanistan for quite some time to come — for one thing, the economy of impoverished Afghanistan is unlikely, for the foreseeable future, to sustain an army big enough to guarantee the country's security. And that's just one of several thorny issues likely to make success in Afghanistan harder to achieve than Iraq — unless the U.S. scales back its ambitious goals for the country. But such a rethink may be on the cards（可能的、即将发生的、注定的）, U.S. military officers say, as internal U.S. reviews and President-elect Barack Obama give the seven-year war a fresh look.

U.S. military officers are already making clear that many of the additional 20,000 U.S. troops bound for Afghanistan in the coming year won't be headed to the Afghan-Pakistani border where the Taliban and its al-Qaeda allies are launching regular and deadly attacks against U.S. and allied troops. Instead, they'll be concentrated on defending the capital, Kabul, from Taliban attack, and also on reinforcing British troops in Helmand and other parts of the south. That will do little to assuage宽慰(人心)、平息(怒气) the criticism that the limited U.S. and NATO deployments in Afghanistan have left Afghan President Hamid Karzai with little more real authority than the "mayor of Kabul", or the reality that the Taliban currently enjoy the momentum.

The U.S. troop "surge" in Iraq may have helped restore relative security there, but the same period has seen a shocking deterioration of the situation in Afghanistan: the Taliban, which controlled 54 percent of Afghanistan in 2007, now controls about 72 percent of the country, according to a new study from the Paris-based International Council on Security and Development, one of the few independent groups that keeps full-time staffers（职员） in the country. That's why U.S. and civilian casualties have spiked in Afghanistan lately after years of being eclipsed by bloodshed in Iraq. There are currently about 32,000 U.S. troops in Afghanistan.

be eclipsed by sth. （sb.）（相形之下）使...黯然失色、使...远不如（某人）

The U.S. scattered（击溃、驱散） the Taliban in the invasion launched a month after the 9/11 attacks, but turned its attention and resources towards Iraq. "As seven years of missed opportunity have rolled by, the Taliban has rooted itself across increasing swathes of Afghan territory," the independent report says. "The increase in their geographic spread illustrates that the Taliban's political, military and economic strategies are now more successful than the West's in Afghanistan. Confident in their expansion beyond the rural south, the Taliban are at the gates of the capital and infiltrating the city at will."

U.S. military officers, speaking privately, concede the bleak outlook in Afghanistan is likely to prompt a scaling back of U.S. goals for the country. The desire to build a strong central government with a large army is likely to be de-emphasized in favor of a provincial structure that relies more on local militias to provide security. "There's a widespread belief in national security circles that the Bush Administration's goals for Afghanistan were too ambitious," says Stephen Biddle, a military expert at the Council on Foreign Relations. "If George W. Bush had served a third term, my guess is that he would be re-evaluating his aims, too."

Biddle recently returned from a trip to Afghanistan at the invitation of Army General David McKiernan, the top U.S. commander. Biddle estimates Afghanistan will need about 500,000 soldiers and police of its own to keep the peace, but U.S. plans call for a force level of about 215,000 (there are roughly 160,000 now). And although the international community will pay for the Afghan security forces while war continues, it won't do so afterward, he says.

Biddle says the military personnel he spoke with in Afghanistan didn't seem to have spent much time assessing how big of an army Afghanistan could support. "It seemed like a new question to a lot of people," he says. "They hadn't spent time computing（计算, 估算） projected Afghan GDP, and the likely percent of GDP they could spend on security, and how many troops that would allow them to support." Biddle says that because Afghanistan can't support a unified force big enough to defend itself, provincial authorities and their militias will have to pick up the slack（使闲散的人力物力充分利用起来）. "Going to a decentralized Afghan end state（最终状态） — with local authorities providing their own security — means the national government's security apparatus can be much smaller," Biddle says. The bad news, of course, is that many such provincial officials are little more than（和……没有差别，一样） warlords, many of whom profit from trafficking in opium. The United Nations estimated last month that the Taliban and its allies — including some of those provincial officials — could clear nearly $500 million in the drug trade this year. But if the U.S. and its allies need to find a way to bring home their own troops while leaving behind a modicum（尤指渴望或有价值之物）少量、一点点 of security, they may find themselves forced to settle for something less than a happy ending（圆满结局）.