The French deserve our thanks for repelling Islamist advances in northern Mali. What they do not deserve is a Pentagon bill for the limited military support we have provided in recent days. Indeed, if it is true, as reported in the French media, that United States has withheld larger deliveries of military assistance until assured of payment, then Washington ought to be ashamed of itself.

In recent days, U.S. transport planes have begun moving French troops and equipment into Mali—two planeloads on Monday, one on Tuesday; and defense secretary Leon Panetta has assured French officials that more can be made available. But the painfully grudging American response to French appeals for help is embarrassing and unbecoming for a superpower supposedly in the vanguard of the struggle against global terrorism.

France is doing the heavy lifting in Mali, because Mali was a French colony and many Frenchmen still live there. It became clear a few weeks ago that Islamist radicals were moving into position to seize the capital city of Bamako. The pathetically inept government of Mali could do little to stop them and requested urgent assistance. The socialist French prime minister, Francois Hollande, though opposed to military intervention and besieged by economic crisis, sent planes, tanks and thousands of troops to Mali. Frenchmen were threatened, and he acted promptly and courageously.

At the same time, Hollande urged neighboring African countries to join French troops in the struggle against Islamist radicals, who for months had been imposing harsh sharia-type law upon northern Mali, amputating limbs, stoning citizens and destroying some of the country’s cultural heritage. Until the French acted, there was a strong possibility that Mali could shortly become an Islamist country governed by al-Qaeda in the heart of central Africa—similar to what Afghanistan was shortly before the 9/11 terrorist attack on the United States.

For this reason, the United States has been very concerned about the rise of Islamist fanaticism in Africa in recent years. Religious fanaticism tied to al-Qaeda terrorism make a very volatile, dangerous mix. The United States has even set up a small but elite force of troops and agents to help fight Mali-type insurgencies in Africa. Is this not the time to use it? One hopes, without fanfare, that it is being used.

The United States might have leaped to France’s support in Mali, but it did not. It limited its military assistance, making certain everyone understood that Washington would not send any troops to Mali; making certain, too, that the French understood that they would have to pay for the limited help they were getting from the United States.

After the wars in Iraq and Afghanistan, the United States has no appetite for further military adventures. In his inaugural address on Monday, president Barack Obama triumphantly proclaimed that “the decade of war” is over, meaning the United States has pulled out of Iraq, is pulling out of Afghanistan, and does not want to get into other wars. It needs a rest. The president has often spoken about the need for “nation-building at home.” That is an understandable position—the American economy is just now beginning to emerge from a deep recession, and the American people are tired. But the the United States remains the only genuine superpower in the world. Whether with joy or caution, it will be called upon to make difficult, controversial decisions. It cannot escape that responsibility.

Wars can be called those of choice or necessity. Either way, some may require U.S. military leadership—and certainly military help. Mali may be one of those wars. The French need American help, and they should get it: transportation, intelligence and even, if necessary, small numbers of special forces that are trained to get into a fight, accomplish their mission and get out. The French should get American help, but not the bill for the help; and they should be heaped with praise for taking on a tough task that no one else, including the United States, seemed ready to do.

Marvin Kalb, a former chief diplomatic correspondent for CBS and NBC, is a guest scholar at Brookings and Murrow Professor Emeritus at Harvard.