The unsung hero of the Libya drama in the U.S. is Secretary of State Hillary Clinton.

Clinton’s actions were critical for several reasons. Most important, she overcame Defense Secretary Robert Gates’s caution about using military force in Libya and his reluctance to support an operation led by France and Britain. Clinton also personally managed the unorthodox partnership with French President Nicolas Sarkozy that proved so crucial to joint action to defeat the Gadhafi regime.

Despite the unusual arrangement in which the U.S. was a supporter rather than a leader of NATO’s military operation, she defended intervention before a skeptical Congress and performed the hard slog of daily diplomacy around the world, helping Arab countries, the Europeans and the U.S. work together with a minimum of friction and a maximum of determination.

Aside from the killing of Osama bin Laden, the decision to support NATO military action in Libya is probably the Obama administration’s most important achievement in international affairs. Although the country is a long way from having a stable, representative government, there is little doubt that the Gadhafi regime has been defeated as a result of an internal revolt led by the Transitional National Council. History will surely judge that, by intervening on the side of the rebellion, the West ― primarily the governments of France, the U.K. and the U.S. ― made a unique and invaluable contribution to the democratic aspirations of the people of the Middle East.

That said, the Obama administration’s decision-making process remains opaque. The veteran journalist Bob Woodward’s next book, due out in the fall of 2012, may shed some light on the question of whose voices were decisive this past March, when President Barack Obama decided to support a United Nations resolution and a NATO military operation for Libya.

Based on our discussions with administration officials, as well as the public record, some preliminary conclusions about the decision are possible. First, while we argued for a more active U.S. military role in NATO’s operation, it is now clear that Obama’s unprecedented approach ― in which Washington supported, rather than led, a NATO operation ― was successful in the end.

Second, by breaking with Gates, Clinton tipped the balance within the administration in favor of action. Without her strong argument to support the Europeans’ call for American help, Washington probably would not have acted. The president’s national security adviser, Tom Donilon, was declaring freedom in Libya to be outside the U.S. national interest, and both military and civilian officials in the Pentagon were reluctant to endorse or even opposed U.S. intervention. But Clinton’s push for the U.S. to act in support of Britain and France appears to have been decisive.

In retrospect, the fears of Gates and other military officials that action in Libya would be a slippery slope, perhaps leading to U.S. involvement on the ground in a third war in the Middle East, seem wildly overblown. Obama said the U.S. would play a limited role by offering unique military assets, such as aerial refueling and air-defense suppression capabilities. Congress not only opposed sending in ground troops but mostly opposed any U.S. involvement. Obama wisely resisted.

For better or worse, the Libya model is not likely to be repeated anytime soon. This is not, as some say, because NATO will never again intervene in a situation like Libya’s. After the Kosovo war, many also said NATO would never again act against a dictator to save lives. The Libya model is no guide for the future because such a unique set of circumstances in favor of military action is not likely to happen again.

Think about the conditions: A despised dictator threatened mass murder; an open desert provided a decisive advantage for air power; a rebel army on the ground sought democratic change and espoused Western values; the U.N. at least loosely endorsed NATO air operations; the Arab League called for the West to intervene militarily in an Arab country; and U.S. allies prepared to do all the heavy lifting. Given those circumstances, it is still hard to explain why there were determined opponents, primarily in the Republican Party, to this mission in the first place.

Throughout most of Obama’s term in office, only a few administration officials have commanded respect and political power on national security matters: Clinton, Gates and General David Petraeus, the most decorated and admired officer of recent times. With Gates now gone and Petraeus in a non-policy role as director of the Central Intelligence Agency, Clinton’s power will only increase as the president’s re-election campaign heats up. We hope she recognizes her opportunity and uses it well.

(Editorial, Bloomberg)