They lounge in folding chairs, perch on traffic bollards or pace small circles to keep warm. They are stationed every 100 feet or so, keeping watch over their designated patch of Beijing street. Their bright red windbreakers and matching armbands spell out their roles as "Neighborhood Security Volunteers.”

Their mission is straightforward: guarantee that nothing disrupts an all-important Chinese Communist Party congress that begins Sunday, where the top leader, Xi Jinping, is expected to claim a third term.

The volunteers, who have blanketed Beijing in recent days, are perhaps the most obvious element of the security blockade that China has imposed on the city. In a country where control is paramount, every preparation is designed to ensure that any perceived threat or wrinkle — from the coronavirus to unsightly litter — is eliminated.