Police around the world, who once routinely handled demonstrations such as Hong Kong's pro-democracy protests with batons and tear gas, face new dilemmas in an age when dissident crowds are armed with smartphones, Facebook and Twitter.

Tough tactics, flashed around the world by social media, can incite demonstrators and undermine a government's legitimacy, as happened in Cairo's Tahrir Square and Kiev's Maidan. Tactics for defusing conflict include avoiding riot gear, deciding early which actions merit arrest and soothing protesters by opening lines of communication, said Chuck Wexler, executive director of the Washington-based Police Executive Research Forum. In Hong Kong, authorities eased an early crackdown, and protesters Monday began allowing access to government buildings.

"The days of a strong show of force no longer apply," said Wexler, whose group consults law enforcement officials to devise model practices. "Today, police have to be much more strategic and think about ways to de-escalate situations."