Last month, a U.S. citizen wearing a Puerto Rico shirt was repeatedly harassed by a man in a state nature preserve as a police officer casually looked on from a distance, a video recently shared on social media showed.

Mia Irizarry rented a pavilion at Cook County Forest Preserves in Illinois for an afternoon picnic on June 14. Not long after arriving, a middle-aged white man approached her and began to harass her about her shirt – a red, white and blue tank top designed like the Puerto Rican flag.

When Irizarry told the man that Puerto Rico is a U.S. territory, he argued back, stepping closer and closer to the woman until he was nearly touching her.

"Are you educated?" he asked gruffly. "Why are you wearing that?"

"Because I can," she responded calmly.

"You're not going to change us, you know that? No, the world is not going to change the United States of America. Period," the man yelled.

"You should not be wearing that in the United States of America. Are you a United States citizen?" he demanded as Irizarry moved out of the pavilion to avoid him.

She responded yes. All those born in Puerto Rico are U.S. citizens.

Just a few meters outside the pavilion, an officer stood with his hands tucked in his belt, watching the encounter.

"Officer, officer, I feel highly uncomfortable," Irizarry pleaded with him. "Can you please grab him? Please? Officer?"

The police officer turned and walked back to his police car without responding, as the irate man followed her out onto the grass.

The harassment continued, as Irizarry repeatedly called on the officer for help, asking, "Is there anything you can do?"

Eventually, more police officers arrived on the scene and she was able to file a report.

The unidentified harasser, who park officers say was intoxicated, was arrested and charged with assault and disorderly conduct. The unresponsive officer seen in the video was reassigned to desk duty pending his conduct review.

Video of the incident went viral, gathering more than 1 million views on Facebook alone.

The U.S. acquired Puerto Rico as a territory in 1899. Those born there are U.S. citizens, although they cannot vote in U.S. presidential elections.

Puerto Rico was hit by a devastating storm, Hurricane Maria, last September. U.S. President Donald Trump came under fire for his handling of the natural disaster, which took the tone of a rebuke to a foreign nation rather than relief efforts for a territory.