The old woman quietly walked over and tapped me on the shoulder that sweltering June afternoon in Ho Chi Minh City. Hair grey, eyes squinting, gums slightly agape, she held up an open can and motioned for me to drink.

What she didn’t know was I had seen her in the company of cong an, the Vietnamese public security forces, minutes earlier. I politely declined. And my co-protester, a young man in his twenties, whispered: “Be careful. Cong an might try to drug you. They’re known to do that.”

The police had pinned me as one of the leaders of the protest. I don’t blame them. As the protests headed from Hoang Van Thu Park, near Tan Son Nhat International Airport, down Nam Ky Khoi Nghia, one of the main thoroughfares leading to the city centre, I moved from documenting the events on my Twitter feed to breaking chains.

At several of the intersections along Nam Ky Khoi Nghia, cong an were throwing up chains of uniformed officers armed with body-length shields. I moved through the crowds and stood right up against them, a phalanx of skinny young men, three to four layers deep. They appeared nervous and scared, and were holding the line only because their superiors were directly behind them, shouting orders. They were vastly outnumbered by the protesters, who were shouting:

• Tags: Issue 13, Vietnam, Will Nguyen