Hong Kong has been living with almost nonstop protests for six months. The movement's demands include democratic elections and an investigation into the police response. More fundamentally, the protesters and others in Hong Kong fear that China is eroding the rights and freedoms they have under a "one country, two systems" framework.

Police say their use of tear gas, rubber bullets and other force is a necessary response to escalating violence by the protesters, who have blocked major roads and thrown gasoline bombs back at officers in riot gear.

The legislation was backed by U.S. lawmakers who are sympathetic to the protesters and have criticized Hong Kong police for cracking down on the pro-democracy movement.

The law, signed last Wednesday by President Donald Trump, mandates sanctions on Chinese and Hong Kong officials who carry out human rights abuses and requires an annual review of the favorable trade status that Washington grants Hong Kong.

The steps are "in response to America's unreasonable behavior," Foreign Ministry spokeswoman Hua Chunying said in Beijing, adding that the legislation seriously interfered in China's internal affairs.

While the nature of the sanctions remained unclear, the move followed Chinese warnings that the U.S. would bear the costs if the Hong Kong Human Rights and Democracy Act was approved.

China said Monday it will suspend U.S. military ship and aircraft visits to Hong Kong and sanction several American pro-democracy and human rights groups in retaliation for the signing into law of legislation supporting anti-government protests in the semi-autonomous territory.

Hua said China would sanction organizations including the National Endowment for Democracy, the National Democratic Institute for International Affairs, Human Rights Watch, the International Republican Institute, Freedom House and others that she said had "performed badly" in the Hong Kong unrest.

"China urges the United States to correct its mistakes and stop any words and deeds that interfere in Hong Kong and China's internal affairs," she said, adding that China could take "further necessary actions" depending on how matters develop.

Hua accused the groups of instigating protesters to engage in "radical violent crimes and inciting separatist activities." "These organizations deserve to be sanctioned and must pay a price," Hua said.

China has long accused foreign groups and governments of fomenting the demonstrations in Hong Kong, singling out the U.S., former colonial overlord Britain, and democratic, self-governing Taiwan, which China claims as its own territory to be annexed by force if necessary.

Among the groups to be subject to the unspecified sanctions, the National Endowment for Democracy receives funding directly from Congress, while others generally draw their running costs from a mixture of private and public grants.

Derek Mitchell, the president of the National Democratic Institute, said in Hong Kong last week that accusations it was colluding with protesters were "patently false." The institute has no role in the current protests, and "to suggest otherwise spreads misinformation and fails to recognize the movement stems from genuine grievances," he said.

China has in the past suspended U.S. military visits, the sanctions on the various groups could bring conditions for civil society in Hong Kong one step closer to those in mainland China. Beijing imposes restrictions on non-governmental organizations, and is particularly concerned about those involved in humanitarian causes, gender equality, the environment or minority rights.

In Hong Kong, several hundred people who work in advertising started a five-day strike Monday to show support for the anti-government protests. They said they would not go to work, respond to work e-mails or take part in conference calls.

Some held up signs with protest slogans at an early afternoon rally to launch the strike in Chater Garden, a public square in the central business district.

Antony Yiu, an entrepreneur in advertising and one of the organizers, said they want other business sectors to join them. "The government seems to be still ignoring the sound of the majority of the people," he said. The advertising industry wants "to take the first step to encourage other businesses to participate in the strike to give more pressure."

More than 10,000 people marched on Sunday to try to pressure the government to address the demands after pro-democracy candidates won a landslide victory in district council elections one week earlier.

Hong Kong leader Carrie Lam has said she'll accelerate dialogue but hasn't offered any concessions since the elections. The protests are blamed for driving the economy into recession. Tourism, airline and retail sectors have been hit particularly hard, with retail sales down about 20 percent.

"The willingness of tourists coming to Hong Kong has been significantly affected," the city's financial secretary, Paul Chan, said Monday. He said the government will run a budget deficit for the first time in 15 years because of falling tax revenues and greater spending to try to offset the economic slowdown.