I did not support the US decision to intervene with military force in Libya. The evidence was not persuasive that a large-scale massacre or genocide was either likely or imminent. Policies other than military intervention were never given a full chance. It was anything but apparent that military intervention would succeed at a level of costs warranted by limited American interests. But we are where we are. So what should the United States do in Libya going forward? American policymakers face a familiar foreign policy conundrum, namely, that there is a large gap between professed US goals and the means it is prepared to devote to realising them. The goals are ambitious: protecting the Libyan people and bringing about a successor regime judged to be preferable to what now exists. But the means are limited, as the president is clearly looking to Americas partners in NATO to assume the major military role and has ruled out the introduction of American ground forces. Whenever there is such a gap between ends and means, a government has two choices: it can either reduce the ends or elevate the means. The Obama administration has up till now mostly emphasised the latter course. The no-fly zone was quickly augmented by additional air operations designed to degrade Libyan government forces. This proved insufficient to tilt the battlefield decisively in favour of regime opponents. Now there is apparent interest in arming opposition forces. I would advise against taking this path. We cannot be confident of the agenda of the opposition towards either the Libyan people or various US interests, including counter-terrorism. Nor can we be certain as to which opposition elements with which set of goals might in the end prove dominant. Arms once transferred can be used for any purpose. Bad situations can always get worse. The only way to ensure the replacement of the current Libyan regime with something demonstrably better would be through the introduction of ground forces that were prepared to remain in place to maintain order and build capacities in the aftermath of ousting the government. As we have seen in Afghanistan and Iraq, the only thing certain about such a policy trajectory is its human, economic, and military cost. US interests in Libya simply do not warrant such an investment on our part. And it is obviously far from certain whether any other outside party has both the will and the capacity to introduce ground forces on a scale likely to make a decisive military difference. There is little reason to conclude that the Libyan opposition will any time soon be able to defeat the Libyan government. It appears to lack the requisite cohesiveness and skill. The combination of a no-fly zone, bombing, and arming might, however, have the effect of levelling the playing field and prolonging the civil war, leading to more civilian casualties in the process. This would be an ironic result of an intervention designed to promote humanitarian ends. The Libyan government may implode, but policy cannot be based on this hope. This all argues for reducing the immediate aims of American foreign policy and giving priority to humanitarian as opposed to political goals. This would entail undertaking or supporting a diplomatic initiative to bring about the implementation of UN Security Council resolution 1973 and, most importantly, a ceasefire. A narrow ceasefire is probably unrealistic, though. What would also be required to gain the support of the opposition would be a set of political conditions, possibly including specified political reforms and a degree of autonomy for certain areas. Sanctions could be added or removed to affect acceptance and compliance. Muammar Gaddafi might remain in office, at least for the time being. The country might effectively be divided for some time. An international force could well be required on the ground to keep the peace. Such an outcome would be derided by some. But it would stop the civil war and keep many people alive who would otherwise perish. It would create a window for political reform and possibly over time lead to a new government without Gaddafi. The United States could use this time to work with Libyans in the opposition and beyond to help build national institutions without the added weight of ongoing fighting. A compromise, negotiated outcome would also be good for the United States, as it would allow it to focus its resources - economic, diplomatic, military, and political - elsewhere. Far more important than Libya for US interests in the region are Egypt, Syria, Bahrain, Saudi Arabia, Iraq, Jordan, and Iran. The United States also needs to reserve resources for other parts of the world (the Korean Peninsula comes to mind), for possible wars of necessity, for military modernisation central to its position in the Pacific, and for deficit reduction. Foreign policy must be about priorities. The United States cannot do everything everywhere. This consideration argued for avoiding military intervention in Libya; now it argues for limiting this intervention both in what it seeks to accomplish and what it requires of the United States. Richard N Haass is President of the Council on Foreign Relations. This opinion piece is based on testimony he gave on April 6 to the Senate Committee on Foreign Relations. Huffington Post