Editor's note: David Cortright is director of policy studies at the University of Notre Dame's Kroc Institute for International Peace Studies and author of the recently released book, "Ending Obama's War: Responsible Military Withdrawal From Afghanistan" (Paradigm Publishers, 2011).
(CNN) -- With Libyan rebels reaching Tripoli, the endgame is at hand. Intense fighting may lie ahead, but the power of the regime appears to be rapidly eroding.
Many questions and uncertainties remain, especially regarding the character of the new regime and whether Gadhafi loyalists go quietly or continue to resist, but one point is clear: The apparent collapse of the Gadhafi government is a major success for NATO and a vindication of President Barack Obama's policy of multilateral humanitarian interventionism.
In making the case for a limited military intervention in Libya, Obama emphasized the moral and political obligation of states to protect those who are victimized by genocide or mass killing, especially when such crimes are perpetrated by their own governments. The principle of the "responsibility to protect" entered the international policy lexicon over the past decade as a response to genocidal killings in Rwanda, Serbia and Sudan.
When governments are unable or willing to protect their citizens, or when governments are terrorizing their own people and committing mass murder, the international community has a responsibility to step in and help those who are victimized.
This principle was endorsed by world leaders at the U.N. World Summit in 2005 and by a resolution of the U.N. Security Council in 2006. Libya is the first example of a formal attempt to implement the principle through multilateral military intervention.
The purpose of intervention in Libya has been to save Libyans from the massacres being perpetrated by the Gadhafi government. In February, the Libyan population rose up against the regime in a completely nonviolent manner, following the example of people in neighboring Tunisia and Egypt, who were able to overthrow corrupt dictators entirely through nonviolent means.
The Gadhafi regime responded to the protests with brutal military attack. Many hundreds were killed as Gadhafi's military forces attacked protesters all over the country. The rebels took up arms to defend themselves but were no match against Gadhafi's army. As the regime's forces closed in on the rebel stronghold in the eastern city of Benghazi, "the Colonel" threatened to annihilate his opponents. Thousands of lives were in immediate jeopardy.
It was at this moment that the international community responded with a commitment to protect the population. In late February, the Obama administration appealed to the United Nations and gained unanimous Security Council support for the imposition of targeted sanctions and referral of the case to the International Criminal Court. The measures adopted by the council were targeted directly at Gadhafi and his family and at key regime loyalists responsible for the mass killing of civilians.
As the crisis worsened, the Arab League took action, adopting a statement declaring that the Gadhafi regime had lost its sovereignty because of its attacks against civilians. The league's statement urged the U.N. Security Council to "shoulder its responsibilities" in imposing a "no-fly" zone and creating "safe zones" in the country. This was an unprecedented action by the Arab League, inviting international intervention against a fellow Arab regime.
Emboldened and encouraged by the Arab League statement, the Security Council took further action. Security Council Resolution 1973 stated that the Gadhafi regime's "widespread and systematic attacks" against civilians "may amount to crimes against humanity" and demanded "an immediate cease-fire and end to all attacks against civilians."
Three months later, the International Criminal Court issued arrest warrants against Gadhafi and one of his sons for crimes against humanity in the massacre of innocent civilians.
All of these actions are unprecedented. Never before has the international community demonstrated such immediate and forceful resolve in responding to government abuse against its own people.
Whether this action will serve as a model for other interventions against brutal regimes is uncertain. Some are asking if the Arab League and NATO should now take action to save the people of Syria from the murderous actions of Bashar al-Assad's regime.
That seems unlikely in the near term, but the apparent success of intervention in Libya may give pause to tyrants who claim the right to massacre their own citizens with impunity. The NATO-led action in Libya may signal a more active international commitment to opposing genocide and mass murder.
The opinions expressed in this commentary are solely those of David Cortright.