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.

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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.

The risks extend beyond electronic communications.

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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.

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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.

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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."

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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. 

FIRST ON FOX: The U.S. Navy is quadrupling the ceiling on a contract for AI-powered robots used to inspect warships to $300 million.

Just six months after initially tapping the technology to help get ships through maintenance and back to sea faster, the expanded agreement with Pittsburgh-based Gecko Robotics underscores the importance the U.S. military is putting on tech-based solutions. The initial ceiling for the deal was $71 million, but the Navy is pushing to improve fleet readiness amid a widening shipbuilding gap with China.

"While the U.S. may not be able to out-manufacture faster than China, we can outsmart the ways that we maintain, operate and are ready with our vessels," Gecko Robotics CEO Jake Loosararian told Fox News Digital.

Gecko says its technology can save the Navy up to $8 million in repair costs on a single ship and identify some structural issues up to 50 times faster than traditional inspection methods.

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The company is also unveiling a new robot developed specifically for the Navy that can inspect the steel beneath thick coatings on warship decks without first stripping them away.

Dubbed Komodo, the robot scans a ship's deck to map corrosion and material thickness, giving maintenance crews a picture of what needs to be repaired before more invasive work begins.

"It's essentially a CAT scan," Loosararian said. "You're basically understanding exactly what's going on."

Traditionally, determining the condition of steel beneath a ship's non-skid deck coating can require removing material before crews know the extent of the problem. Komodo is designed to gather that information without first taking the surface apart.

"The robots are able to actually understand what's wrong without having to take apart the ship to figure out what to fix," Loosararian said.

In another example cited by Loosararian, an assessment that initially called for roughly 1,200 square feet of repair work was narrowed to about 300 square feet after robotic inspections provided a more precise picture of the damage.

"You reduce and focus the kinds of repairs that you need," Loosararian said. "You're repairing less."

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The increased ceiling comes just six months after the Navy awarded Gecko a five-year, $71 million contract vehicle to expand the use of its robotic inspection technology across the fleet.

Under the initial agreement announced in March, Gecko was set to begin work on 18 ships in the U.S. Pacific Fleet, including destroyers, amphibious warships and littoral combat ships.

The company's wall-climbing robots crawl across hulls, flight decks, ballast tanks and other difficult-to-access areas, scanning for corrosion, metal loss and other structural problems. The data is fed into Gecko's AI-powered Cantilever platform to help maintenance planners determine where repairs are needed.

The goal is to find those problems earlier, before a ship enters a major maintenance period and crews discover additional work that can extend its stay in the shipyard.

"The biggest savings are just in speed," Loosararian said. "Speed — you can't put a price tag on it, especially if you're in the U.S. Navy right now."

The expansion comes as Navy leaders seek to push fleet readiness toward 80% while maintenance delays continue to sideline ships that would otherwise be available for deployment.

China already fields a larger battle force than the U.S. Navy and can produce vessels at a pace American shipyards cannot easily match. That has put additional pressure on the Pentagon to keep more of the ships already in the American fleet available for operations.

For Gecko, the longer-term goal is to move beyond finding existing damage and use years of inspection data to anticipate problems before they force ships into longer repair periods.

"You are able to predict exactly what's going to break before it does," Loosararian said, allowing maintenance planners to have workers, materials and repair plans ready when a ship reaches the pier or enters a shipyard.

The technology could also reduce the amount of dangerous and labor-intensive inspection work performed by shipyard workers as the industrial base struggles with shortages of skilled labor.

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Loosararian said the combination of robotics and AI is ultimately aimed at allowing a limited workforce to spend more time fixing ships and less time determining what needs to be fixed.

For a Navy racing to keep pace with a rapidly expanding Chinese fleet, he argued, getting more out of the ships already in the water could prove just as important as building new ones.

"While the U.S. may not be able to out-manufacture faster than China," Loosararian said, "we can outsmart the ways that we maintain, operate and are ready with our vessels."

The founder of Christian human rights organization ChinaAid is raising concerns over the health of an imprisoned Chinese pastor who may be suffering from advanced liver cancer, and his family continues to face restrictions on visitation and access to medical information.

Rev. Dr. Bob Fu, founder and president of ChinaAid, told Fox News in an interview that reports concerning Pastor Wang Yi's health are "very worrying," citing information received from multiple sources inside China.

Wang, the founding pastor of Early Rain Covenant Church in Chengdu, has been imprisoned since December 2018 and is serving a nine-year sentence on charges of inciting subversion of state power and illegal business operations.

Although Fu believes that reports of advanced liver cancer are credible, he acknowledged that his organization has not been able to independently confirm the diagnosis.

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Fu said ChinaAid was "not able to really independently verify" the reports, citing restrictions on access to Wang and the absence of an independent medical examination.

The organization first publicly raised concerns about Wang's condition on Sept. 28, calling on Chinese authorities to provide his family with access to him and disclose information about his medical treatment.

During the interview, Fu revealed that authorities reportedly provided information by telephone about medical examination they claimed had been conducted on Oct. 1.

According to Fu, prison officials cited medical information indicating Wang was in good health. However, his family has not been permitted a new in-person visit to independently assess his condition.

Fu said that, despite repeated letters from Wang's wife and relatives requesting access, "no meeting had been granted at all" since the latest health concerns emerged.

The pastor's church has also expressed uncertainty about his condition.

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In an Oct. 3 open letter, Early Rain Covenant Church acknowledged the reports but said it could not determine whether Wang had fallen ill. The church called on prison authorities to permit regular family visits, correspondence and telephone calls, as well as provide information about any necessary medical care.

According to the church, Wang's family has been permitted fewer than five visits during nearly eight years of imprisonment.

Fu likewise described severely restricted visitation, saying meetings have been brief and closely monitored by authorities. He alleged that discussions concerning Wang's health or religious beliefs have resulted in visits being abruptly terminated.

"Two years, not a single letter for his wife," Fu said, describing the restrictions on communication.

"That's not acceptable. That's even a violation of its own law."

Wang was arrested Dec. 9, 2018, during a crackdown on Early Rain Covenant Church, an independent Protestant congregation operating outside China's state-regulated religious systems.

In December 2019, a Chinese court sentenced him to nine years in prison. The U.S. State Department condemned the conviction at the time, describing the prosecution as connected to Wang's peaceful advocacy for religious freedom and calling for his release.

The U.S. Commission on International Religious Freedom lists Wang as a religious prisoner of conscience and has documented reports of medical neglect.

Fu also raised concerns about the treatment of Wang's wife, Jiang Rong, who was detained during the initial crackdown.

He said Jiang had previously been subjected to residential surveillance at a police-arranged location rather than being allowed to remain in her own home and described the lasting emotional consequences of her treatment.

Fu said he believes the severity of the reports warrants immediate action, particularly given the limited access to Wang.

He called on the Chinese authorities to permit Wang's wife, son and elderly parents to meet with him privately, allow an independent medical examination in the presence of legal counsel and release his medical records, including information concerning medications administered during his imprisonment.

Fu also expressed concern about reports of mistreatment of other prisoners of conscience, including allegations of forced medication and serious physical and psychological harm. Those allegations were discussed as part of his broader concerns about the treatment of detainees in China, rather than as established evidence of what has happened to Wang.

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The ChinaAid president urged the Trump administration to raise Wang's case directly with Chinese officials during upcoming diplomatic engagements.

"I really want to see the Trump administration to continue to speak up forcefully," Fu told Fox News, calling for the names of individual prisoners of conscience to be included in high-level discussions.

He pointed to the July release of Pastor Ezra Jin Mingri, who was reunited with his family after President Donald Trump raised his case with Chinese President Xi Jinping during a May visit to Beijing.

Fu believes that example demonstrates the potential importance of direct diplomatic intervention, although the circumstances of Jin's release do not establish that such pressure would produce the same result in Wang's case.

Trump and Xi are expected to attend upcoming international summits, including the Asia-Pacific Economic Cooperation leader's meeting in Shenzhen, China, in November and the G20 summit in Miami in December.

Fu urged U.S. leaders not to allow trade and security negotiations to overshadow concerns about religious freedom, human rights and the treatment of prisoners.

"I think it's time to hold them accountable," Fu said.

In a statement to Fox News, Chinese Embassy spokesperson Liu Chang said the embassy had no information to provide regarding Wang's specific case.

The spokesperson defended China's religious policies, saying the government protects freedom of religious belief under Chinese law and does not interfere in religious groups' internal affairs.

Liu added that China prohibits illegal activities carried out under the guise of religion and opposes foreign interference in its domestic affairs.

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The embassy did not directly address questions about Wang's reported medical condition, family visitation or the possibility of an independent medical examination.

The U.S. State Department did not respond to Fox News Digital's request for comment by publication time.