During four hard combat tours as a Marine commander, Jake Harriman began to understand why the United States is failing to eradicate violent Islamic extremism.

Individual heroics and immense sacrifice over 16 years have enabled American combat troops and special forces to win their battles with the Taliban, al Qaeda and the Islamic State. Those extremist militias are virtually powerless against U.S. drones and airstrikes, which have killed dozens of senior leaders. But still, jihadist movements persist and grow.

Afghan kids keep joining the Taliban, which controls a growing swath of Afghanistan. ISIS, despite battlefield setbacks, recruits passionate believers in Syria, Afghanistan and Libya, not to mention Manchester, England, and Minneapolis . Extremist militias across Africa, around the Middle East and in Southeast Asia draw volunteers. And terrorism continues.

What Jake Harriman and his fellow Marines saw was that the United States, for all its battlefield prowess, does not recognize or act on the causes of violence.

But the extremists do.

We were going out every night on these snatch-and-grab missions and we began to see we were taking three steps forward, two steps back. The guys we were fighting were out in these villages winning hearts and minds, Harriman, 42, told HuffPost. They were dropping off food, they were building schools, they were building clinics. And yes, they were horribly oppressive. But these vulnerable populations were so impoverished that the parents had no other choices to feed their kids.