The impoverished, landlocked country of Chad has a tendency to spar with its neighbors and worsen their conflicts. But when 400 of its tanks rolled across the border and into Cameroon in January, something strange happened: Thousands of Cameroonians came out to cheer them on.

Has there ever been an unlikelier hegemon? Compared with Nigeria, its powerhouse neighbor to the south, Chad has so little. Its population is a mere 13 million, and its gross domestic product is 37 times smaller. When the U.N. ranked 187 countries on the Human Development Index, Chad landed at 184. But where Nigeria has failed … and failed … to vanquish Boko Haram, Chad’s military — versed in guerrilla warfare and supported by Western powers — has made surprising progress. It’s just the latest in a series of military ventures that have extended Chadian influence, and though it’s too early to know whether this will be good or bad in the long term, one thing is clear: There’s little like a terrorist group that lays waste to villages and kidnaps schoolgirls to reconfigure power in a region.

Chad’s leadership against Boko Haram is a relief for America and Europe, which desperately want to avoid deeper involvement

The jihadi group Boko Haram, which emerged in northeastern Nigeria, initially focused on local grievances. But over the past year, it has seized territory throughout the region and provoked essentially a multinational war. Throughout 2014, it became clearer to Nigeria’s neighbors and Western partners that Nigeria couldn’t go it alone. (Indeed, President Goodluck Jonathan arguably paid for this failure in his unsuccessful re-election bid.) After Boko Haram began launching attacks in northern Cameroon and southern Niger, Chad went on the offensive. Its troops led an attack in February in the Nigerian town of Gambaru, a base for Boko Haram cross-border raids into Cameroon, and wiped out scores of militant fighters. In early March, Chad and Niger freed two other northern Nigerian towns from the group’s clutches.

How to explain Chad’s military success? Martin Ewi, a senior researcher at the Institute for Security Studies in Pretoria, South Africa, says it comes down to discipline. Unlike in Nigeria, “the military has been at the center of everything that is Chadian,” he says. It also helps that Chadian soldiers train in guerrilla tactics and in the unforgiving conditions of the Sahara Desert, which stretches across roughly two-thirds of the country, Ewi says: They’re particularly suited to taking on the smaller-scale conflict presented by terrorism.

Chad’s military has built up muscle over half a century, testing itself against regional conflicts and internal rebellions. In the ’70s and ’80s, fighters battled Libyan-backed Muslim rebels in the north, and internal uprisings have popped up since. Autocrat Idriss Déby, who seized power in a coup in 1990, has contained them through force. The discovery of oil reserves has also boosted military investment. But part of Déby’s strategy involves extending Chad’s influence abroad. In recent decades, Chad has intervened in rebellions and civil wars in neighboring Sudan and the Democratic Republic of Congo. Most notoriously, it sent troops into the Central African Republic last year, ostensibly to stop a genocide in the making. But both the U.N. and Human Rights Watch found evidence that Chadian soldiers worked with Muslim fighters to target and kill Christian civilians.

Déby, however, has earned the loyalty of the West by helping fight terrorism. Chad’s leadership against Boko Haram is a relief for America and Europe, which desperately want to avoid deeper involvement; France, in particular, has provided key financial support and training. Chad is home base for the French military’s Operation Barkhane, a counterterrorism effort launched in Africa last year, and its military was a key part of the French operations that uprooted al-Qaida from Mali in 2013. That “really asserted Chad as a massive regional player, specifically Déby himself,” says Ryan Cummings, chief Africa analyst at the risk analysis firm Red24. Later in 2013, Chad was elected to one of the rotating seats at the U.N. Security Council. It’s just one of “multiple benefits to being a reliable Western partner,” says Cummings, who is based in Cape Town, South Africa.

But the longer-term consequences of Chad’s newfound dominance are uncertain. Sarah Margon, Washington director at Human Rights Watch, says Chad and its partners deserve credit for taking on terrorists, but worries about their poor records for protecting civilians. There’s also the question, Margon says, of “how they play with others.” So far, Chad’s forces have been welcomed with open arms by Cameroon, Niger and, grudgingly, Nigeria. Chad’s leaders insist they’re not interested in occupation. But what happens if their military does, in fact, stick around after Boko Haram leaves town?

This spring, the African Union, with help from the U.N., will begin overseeing the West African military offensive against Boko Haram, bringing a more official structure to the battle. That means the Chadian army, which will be the largest force in this A.U. effort, will have to play by international rules — meaning no more impunity for human rights violations or meting out extrajudicial justice. “If you’re an optimistic person,” says Margon, “this is Chad’s opportunity to show they can do it.”