Many Democrats, meanwhile, are urging Obama not to send more troops to Afghanistan. Some in his own administration, notably Vice President Joe Biden, aren't convinced that more troops would guarantee success and advocate instead more drone attacks and more training for Afghan forces.

Training Afghan troops, police and border guards, however, is proving to be a slow and frustrating process, hampered by corruption, illiteracy, ethnic rivalries and logistical problems, and carried out in the shadow of doubts about what kind of government the troops are serving.

Finally, Obama must reckon with domestic economic pressures. The unemployment rate reached 10.2 percent in October, the highest since 1983, and there are growing fears that changes in the nation's health care system could send the federal budget deficit even higher.

Obama campaigned saying that he'd fund the Iraq and Afghanistan wars from the defense budget, but Adm. Michael Mullen, the chairman of the Joint Chiefs of Staff, said last week that the Afghan war — which some administration officials privately concede could cost $700 billion to $1 trillion — might require a supplemental funding bill next year. Among the cost estimates the Pentagon is considering is $1 trillion over 10 years, two senior defense officials told McClatchy.

Because of these pressures, it's become "highly likely that the administration would send more troops," said Paul Pillar, the director of Strategic Studies at Georgetown University. "Then it is a matter of degree," particularly given the struggling U.S. economy.

For all the debate and deliberation, however, the proposed new deployments still may not answer the fundamental question about Afghanistan, Pillar said: Would a Taliban-controlled Afghanistan pose a threat to the United States?

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