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Trump takes questions on China trip
President Trump took questions on Air Force One as he took the long trip back to the White House from China.
Americans traveling to China are being warned about the possibility of detention, electronic surveillance and restrictions that could keep them from returning home, with a travel expert sharing critical information for people to know before they go.
The U.S. State Department issued an updated Level 2 "Exercise Increased Caution" advisory for mainland China this week, citing concerns about wrongful detention and restrictions on leaving the country.
Travelers are told to be aware that routine professional, academic and personal activities, which carry no risk in Western countries, could be treated as criminal offenses under China's broad security laws.
STATE DEPARTMENT ISSUES TRAVEL ADVISORY AS ARRESTS AND EXIT BANS HIT POPULAR DESTINATION
The advisory also raises concerns about private communications, warning Americans that emails, texts and social media activity could be monitored by Chinese authorities.
"Assume that China's security services can read your emails, texts and social media posts if you send them to or from China," the Oct. 19 advisory states.
The State Department said some people have been detained or deported over private messages considered critical of Chinese authorities, even when those messages were sent outside China.
Americans traveling to China are being warned about the risk of detention and restrictions that could prevent them from returning home. (Ju Huanzong/Xinhua via Getty Images)
The risks extend beyond electronic communications.
The State Department elaborated on possible detention without justification.
"The U.S. Department of State has determined that Americans are at serious risk of wrongful detention by the Government of China," the advisory states.
Those detained could spend years behind bars with limited contact with family members or U.S. officials, according to the department.
Travelers could also face restrictions that prevent them from leaving the country, even if they have not been detained.
Chinese authorities have used the "exit bans" during investigations and business or civil disputes. Exit bans have also affected relatives of people under investigation, including children, according to the advisory.
Some travelers may not know they're prohibited from leaving until they try to fly home.
"U.S. citizens might only become aware of an exit ban when they attempt to depart China," the State Department said.
Some bans have lasted for years. Officials warn there may be no clear way to challenge them in court.
Americans who plan to visit China are advised to travel with a U.S. passport and valid Chinese visa, enroll in the Smart Traveler Enrollment Program and arrange regular check-ins with family members or an employer.
Fox News Digital reached out to the U.S. State Department for further comment.
"Be aware of your surroundings. Think before you take a picture," advised Bobby Laurie, a longtime travel expert and former flight attendant.
"This is one of those situations where maybe you were spotted taking pictures of law enforcement on the street, or you were somewhere you shouldn't have been. Maybe you were inadvertently near a protest on the streets," he added.
"Then as your trip comes to an end, you head to the airport. You scan your boarding pass, ready to get through immigration to fly home. And then you realize you're actually not allowed to fly home. There has been an exit ban placed on you."
He said anyone traveling to China should go with "a cell phone or electronic device that is really stripped down just to what you need for your trip."
Leave confidential information at home, he also urged.
Find more updates on this story at FOXNews.com.