In the aftermath of the September 11 attacks, the United States quickly deployed troops and military assistance to a large part of West Africa to support French forces in combatting the expansion of Al Qaeda and other terrorist organizations.

More than a decade later, and with hundreds of millions of dollars in security assistance spent, that regional counterterrorism effort has largely failed.

Groups that have declared allegiance to Al Qaeda and the Islamic State are on the march. Military coups have toppled civilian-led governments in Mali, Guinea, Burkina Faso and Niger. The new leaders have ordered American and French troops out, and in some cases invited Russian mercenaries  in to take their place.

As the United States withdraw 1000 military personel from Niger and shutters a $100 million air base  there by September, American officials are scrambling to work with a new set of countries in coastal West Africa to battle a violent extremist insurgency that they perceive is steadily seeping south.

“Of course, it’s frustrating, the Pentagon’s top official for special operations policy, said in an interview. “Our general desire to promote democratic governments and having healthy governance there has not gone particularly well.”

The U.S. military has had more success training local counterterrorism troops, Mr. Maier said, although some participated in the recent military takeovers. But, he added, “it’s disappointing when we’ve invested in that relationship and then we’re asked to depart.”

U.S. officials say they are retooling their approach to combat an insurgency that is rooted in local, not global, concerns. Competition for land, exclusion from politics and other local grievances have swelled the ranks of the militants, more than any particular commitment to extremist ideology.

Instead of relying on big bases and a permanent military presence, officials say that the strategy will focus more on well-financed initiatives that include security, governance and development — paying for soldier training as well as for new electrification or water projects.

This kind of holistic approach has been tried before with limited success, and U.S. officials and independent West Africa specialists say it faces steep hurdles now.