What next in Libya? President Obama has yet to outline a clear and certain course. The best option would be to minimize the commitment of the U.S. military, look after the best interests of Libya's civilian population, and limit the spread of terrorism and instability throughout the region. The question is how.

First, the president must clearly articulate the mission of U.S. operations in Libya and clarify U.S. interests. A clear declaration of purpose is vital to avoid "mission creep" - an expansion of commitments beyond the original goal of the operation. The United States does have legitimate interests in the outcome: bringing Moammar Gadhafi to justice, ensuring the country doesn't become a terrorist haven, preventing a humanitarian crisis and a wave of refugees that could overwhelm our European allies, stopping the spread of civil war to bordering nations.

But these concerns fall short of vital interests that would justify significant, protracted operations by U.S. forces and can be addressed through measures short of war. Even at this point, it's difficult to endorse further military operations without a clear understanding of their scope and purpose.

In any military operation, initial plans never survive first contact with the enemy. This was seen hours after the vote in the U.N. Security Council resolution when Gadhafi tried to forestall military action by unilaterally declaring a cease-fire. Military planners should lay out "branches" (alternative plans if the initial ones fail) and "sequels" (follow-on plans to exploit success). For example, what would the United States do if Gadhafi's regime collapses? What would the United States do if Gadhafi launches terrorist attacks against the United States or its allies? Congress and the White House should seek common ground now - not after the president announces the next troop deployments - on what is prudent.

The United States should no longer recognize the government in Libya. Limiting the capacity of Gadhafi's military was always well within the capabilities of coalition forces backed by the United States. The question has always been: What comes next? If the United States and other interested nations wish to avoid protracted military engagement, they must position for success by identifying and supporting a "legitimate" opposition that is free from terrorist taint.

It's too soon to determine whether the opposition should be backed with sufficient resources and support to storm Tripoli - a rush to Tripoli by a disorganized and ill-prepared military force might only serve to exchange the threat of a humanitarian crisis in Benghazi for one in the capital - or be given adequate support to defend itself. Neither of these options would be cheap or risk free, but they are more manageable than protracted U.S. engagement.

Likewise, supporting the opposition would include expanding its capacity to govern, provide goods and services, and restore the Libyan economy.

In this manner, as the rebels expand their authority in the country, they will be able to do so in a manner that looks after the civilian population - a better solution than enforcing an immediate regime change, which might result in chaos and put the whole population at risk.

Supporting the opposition may require circumnavigating the prohibition against arming them in U.N. Security Council resolutions (Resolution 1970 prohibited the supply of arms to anyone in Libya; Resolution 1973 is ambiguous).

Meanwhile, the United States should continue to work to isolate Gadhafi's regime in every way possible with the goal of one day bringing him to justice. Libya's neighbors have the most to lose if Gadhafi remains in power, or if parts of Libya becoming a terrorist safe haven and training ground. They should bear the majority of the cost and responsibility for support going forward.

Britain and France will - it is hoped - assume responsibility for the bulk of air support duties, backed by Denmark, Norway, Spain and as many Arab countries as possible. Wealthy members of the Gulf Cooperation Council - the first international body to call for military action in Libya - should help finance the operation, if not send their own warplanes to enforce it.

If Gadhafi remains in power, he will undoubtedly seek revenge against his enemies. He may seek to reacquire weapons of mass destruction technologies. Likewise, al-Qaida could, as it has sought to do elsewhere, seek to use the country as a battleground to recruit and train terrorists.

The United States must be prepared to deal with terrorists trying to smuggle foreign fighters into Libya or arms and support to Gadhafi. There is no magic button for solving the problems of Libya. No option is risk-free. The Obama administration and Congress, however, should adopt the most prudent course. Protecting U.S. interests and playing a positive role in the region will require limited but long-term engagement.

James Jay Carafano is deputy director of the Kathryn and Shelby Cullom Davis Institute for International Studies and director of the Douglas and Sarah Allison Center for Foreign Policy Studies, a division of the Davis Institute, and James Phillips is senior research fellow for Middle Eastern Affairs in the Allison Center at The Heritage Foundation.