The US State Deparment is warning travelers to exercise "increased caution" in Hong Kong amid ongoing protests.

Pro-democracy demonstrators have crippled the city's airport for days, forcing hundreds of flight disruptions.

China appears to be gearing up to take forceful intervention to stop the protests.

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The United States government is warning citizens to exercise "increased caution" in Hong Kong as pro-democracy demonstrations in the city enter their ninth straight week.

"Most have been peaceful," the state department said of the protests that crippled air travel in the semi-autonomous financial center this week, "but some have turned confrontational or resulted in violent clashes."

"Police have used a variety of crowd control measures, including the deployment of tear gas," it continued. "The protests and confrontations have spilled over into neighborhoods other than those where the police have permitted marches or rallies. These demonstrations, which can take place with little or no notice, are likely to continue."

If you are traveling to or within Hong Kong, the agency suggests avoiding areas where demonstrations are taking place, keeping a low profile, and being aware of your surroundings.

Read more: The risk of traveling to every country in Asia, according to the US State Department

Protests began in June in Hong Kong against a proposed law that would give China power to extradition people in the city who were accused of crimes. The bill was later rescinded, but not done away with completely. The demonstrations have since morphed into a wider, pro-democracy showing.

China, meanwhile, appears to be ready to forcefully intervene in order to stop the protests. The country's military has been assembling troops and supplies along the border with Hong Kong, and the Chinese government previously called the protests "near-terrorist acts," according to Reuters.

The Level 2 advisory is the second tier of the State Department's warning system, with the third urging citizens to reconsider travel, and the highest warning telling travelers to avoid the region entirely.

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