In the open bed of a pickup truck, half a dozen soldiers were bouncing along a country road in eastern Ukraine when one of them yelled, “Drone!” They all opened fire with their rifles, yet hitting the tiny, swerving speck carrying death was all but impossible.

Buzzing in fast, within seconds it was only about a yard away. In that moment, captured on a helmet camera on a crystalline spring day, the soldiers seemed doomed. In a desperate act of self-defense, one of them, an American, Pvt. Zachary Miller, hurled his empty rifle at the drone — and missed, he said in an interview.

They may never know why, but at the last moment, it veered away, sparing them. “Yes! Yes! Yes!” the soldiers shouted, in English, in the video, which was later posted online by the Ukraine military.

The flow of American volunteers like Private Miller serving in the Ukrainian military dwindled but never stopped after the initial wave that followed the Russian invasion in 2022. Independent estimates of the number of Americans volunteering since 2022 have varied widely, from more than 1,000 to several thousand. The Ukrainian military does not release figures.

But over time, the makeup of American volunteers has shifted, with higher proportions of people who have no military background, are older or are U.S. veterans seeking to restart military careers closed off to them at home because of age or injuries.

Interviews with American enlistees, aid workers who help them and their Ukrainian commanders reveal an array of motivations. Some come looking for purpose and possibilities they found lacking in dead-end jobs back home. Outrage at Russian aggression remains high on the list of reasons, while some soldiers are looking for a way to leave behind troubled lives. Still others want second chances at military careers and to test themselves in combat.