Hong Kong faced a new reality on Wednesday as China began enforcing a sweeping security law that could reshape the financial hub’s character 23 years after Beijing took control of the former British colony.

The new law’s provisions went beyond what many investors, democracy advocates and even pro-Beijing politicians expected, prompting warnings it would have a chilling effect on free speech and political activities related to Hong Kong. Leaders in Beijing and Hong Kong did nothing to allay those worries during briefings to explain the 35-page law which was first unveiled as it came into effect late Tuesday, even as thousands hit the streets in defiance.

"The law is a ‘sword of Damocles’ hanging above extremely few criminals who are severely endangering national security,” Zhang Xiaoming, the deputy director of the Hong Kong and Macao Affairs Office, told reporters Wednesday in Beijing. "The law will deter foreign forces who try to interfere with Hong Kong affairs. The law is a turning point to put Hong Kong back on its track.”