The Bush Administration's approach to Afghanistan has been to work with Pervez Musharraf of Pakistan. While this may have spawned early success, it has clearly gone beyond the point of diminishing returns. With the increased level of unmanned aerial attacks, it's clear that the CIA, at least, has realized the limits of this approach and is exploring new ways of dealing with the problem of radical Muslim terrorism in the region.
With the terrible terrorist attacks on Mumbai, a new variable has been thrown into the equation. Some in India are angrily calling for war with Pakistan. Such a war would undoubtedly escalate into something larger, including the disputed Kashmir and Northern Areas.
This may be where the opportunity lies for the U.S. Of course no one outside the intelligence community is privy to the level of co-operation between the U.S. and India, but given that the focus has been a tactical alliance with Pakistan, my guess is that the connection with India has at a minimum been weakened. There are a myriad of opportunities available for the U.S. They could act as a peace broker between the two nations, fostering some goodwill in the process. They could take the opportunity to greatly strengthen ties with India. That would serve not only as a potential base of operations if Pakistan falters in it's support, but also, strengthened ties and a strengthened India (with respect to intelligence, trade, security, military and economically) would provide a regional counterbalance to the threat of an aggressive China. In the event of a war in the Kashmir and Northern Areas, supporting India might provide further opportunity to ferret out Bin Laden, in another area he could be in hiding.
Of course there a number of threats in these scenarios as well - a regional conflict may drag the Chinese into the Kashmir territory dispute. Another war front is simply unaffordable, especially during a recession. America may be forced to stand on the sidelines and the outcome would probably not be to their liking. Not gaining Indian support and losing support in Pakistan would severely impede operations in Afghanistan.
Afghanistan is 1 1/2 times the size of Iraq, with 116% of Iraq's population, much less hospital terrain and about 20% of the amount of paved roads. Creating a stable Afghanistan has massive logistical problems as it is, losing a base of operations like Pakistan would pose incredible challenges. Even if India were to offer an opportunity along those lines, it would be exponentially more difficult logistically, given the distance between the base of operations and the area of operations. The remaining scenario is ramping up in Afghanistan to levels greater than in Iraq if the job is to get done properly. Given the geographic obstacles, the dangers to U.S. troops would be quite great.
If a regional conflict were to occur, Russian action might also be a possibility. It's a situation that could very quickly spiral out of control, and one where the U.S. is not in the best position to achieve it's regional objectives.
The United States is currently holding a weak hand at the table in many respects. It cannot finance further activity, it cannot rely on continued support from Pakistan in light of the Mumbai attacks, and recent comments from Pakistani military officials. Really negotiation and peace brokering are it's only options at this point, which are also weakened because the others at the table will know that the American 'big stick' isn't in play. The terror attacks in Mumbai are tragic, but they also represent a minefield that needs to be negotiated very skillfully if the United States wants to accomplish anything positive, or even avoid a possible flash point of a new threat to regional stability.