WASHINGTON, D.C. ― Leaders around the world are vigorously debating the advisability of establishing a no-fly zone to stop the violence unfolding in Libya. Some cite Bosnia, where NATO took too long to protect civilian populations in the mid-1990’s, as a reason to act. Others remember Rwanda, where President Bill Clinton later expressed regret for not acting to save innocent lives. But the stakes in Libya today are more appropriately underscored by the tragedy in southern Iraq in the waning days of the Persian Gulf War 20 years ago.

As coalition forces were routing the Iraqi army in February 1991, President George H.W. Bush encouraged the Iraqi people to “take matters into their hands to force Saddam Hussein the dictator to step aside.” When Iraqi Shiites, Kurds, and Marsh Arabs rebelled against Hussein, they believed that American forces would protect them against their brutal dictator’s superior firepower.

Instead, when Iraqi attack helicopters and elite troops began butchering their own people, coalition forces were ordered to stand down. The world watched as thousands of Iraqis were slaughtered.

The situation in Libya today is not identical. Inspired by events in Tunisia and Egypt, the Libyan people rose up spontaneously against four decades of repression by Col. Moammar Gadhafi. Still, the specter that haunts me is the same ― ordinary people facing off against an autocrat’s airpower and well-armed soldiers, counting on the free world to protect them against massacre after we have applauded and bolstered their bravery with our words.

So far, Gadhafi’s forces have relied on airpower selectively. But Gadhafi is shrewd. My fear is that he is either choosing to bleed the opposition to death, rather than invite global action with a broad massacre, or waiting for the world to prove itself unwilling to act ― at which point he might well begin killing civilians in large numbers.

We cannot wait for that to happen. We need to take concrete steps now so that we are prepared to implement a no-fly zone immediately if Gadhafi starts using his airpower to kill large numbers of civilians. Diplomacy is urgently needed to build broad support for a no-fly zone.

The most important imprimatur should come from the United Nations, where debate should begin immediately over a resolution authorizing a no-fly zone. China and Russia have expressed reservations. If the Security Council fails to authorize action, those of us determined to protect Libyan civilians will face a more difficult choice should the violence escalate.

So our diplomatic efforts must extend beyond the U.N. The support of NATO and the African Union are important. To avoid the perception of NATO or the U.S. attacking another Muslim country, the backing of the Arab world is also needed.

On that front, there are promising signs. The six Arab countries of the Gulf Cooperation Council have called for a U.N.-imposed no-fly zone. The Arab League may consider a similar proposal. Muslim countries in particular should support preparations for intervention if the violence spirals out of control.

Gadhafi cannot be allowed to think that he can massacre his people with impunity. And he cannot be free to make those attacks more lethal by using his airpower. If the U.N. cannot approve a resolution for implementing a no-fly zone, then the U.S. and its allies in NATO and the Arab world must be prepared to prevent a massacre like the one that occurred in Srebrenica in 1995, when more than 8,000 Bosnian men and boys were slaughtered.

Of course, imposing a no-fly zone would not be a panacea. It probably would not tip the balance if the situation in Libya deteriorates into a full-scale civil war. But a no-fly zone would eliminate airstrikes and save civilian lives. It is a tool that we should be ready to use if the situation warrants it, and it would signal to the opposition that it is not alone.

Before that decision is reached, the international community needs to provide humanitarian assistance and medical supplies to the rebels in eastern Libya. We must not allow them to be starved into submission.

The one option that should not be on the table is U.S. ground troops; no one wants to see U.S. forces bogged down in another war, especially in another Muslim country. And, as President Barack Obama has said, the Libyan people must not be deprived of full ownership of their struggle for freedom, and Gadhafi must not be given a useful foil and scapegoat.

Perhaps the mere threat of a no-fly zone will keep Gadhafi’s pilots from using their helicopters and fighter jets to kill their own people. If it does not, we should make clear that we will lead the free world to avoid the senseless slaughter of any more Libyan citizens by a madman bent on maintaining power. The U.S. and the world community should also make clear ― as we did in Bosnia and Kosovo ― that we are taking a united stand against a thug who is killing Muslims.

By John Kerry

John Kerry, a U.S. Senator from Massachusetts, is Chairman of the Senate Foreign Relations Committee. ― Ed.

(Project Syndicate)