HORLIVKA, Ukraine — In a video posted online Monday, a man wearing an unmarked green uniform calls to attention a squad of Ukrainian policemen who have just switched over to the pro-Russian side in this eastern Ukrainian town.

The uniformed man is one of hundreds of militants who have seized government buildings in eastern Ukraine. His identity soon becomes clear, a rarity in a mixed force of uncertain origin or origins. Some of the men are well armed and disciplined, leading to Western assertions that they are not merely equipped or inspired by Russia but in fact Russian soldiers, as was the case in the occupation of Crimea, where they became known as the Green Men.

Yet in eastern Ukraine, the Green Men are different; many or even most appear to be locals.

Still, some ties to Russia are unmistakable. In the video posted Monday, when the uniformed man at the police station identifies himself as a lieutenant colonel, a policeman asks, “a lieutenant colonel of what?”

“Lieutenant colonel of the Russian Army,” the man replies. “Good afternoon, men.”

It was a rare moment of clarity. Journalists who watched the video, posted on YouTube and titled “Horlivka police go over to the occupiers,” had seen the same man outside the police building earlier in the day.