Emily Feng

This August, Aibota Zhanibek received a surprising call in Kazakhstan from a relative through Chinese chat app WeChat. It was about her sister, Kunekai Zhanibek.

Aibota, 35, a Kazakh citizen born in China, knew that Kunekai, 33, had been held for about seven months in a detention camp in China's Shawan county, in the northwestern region of Xinjiang. For six of those months, Kunekai was forced to make towels and carpets for no pay, Aibota says. On the call, Aibota was told that Kunekai had been released and assigned a job in Urumqi, the capital of Xinjiang.

Hundreds of masked protesters peacefully marched through Hong Kong's central business district Saturday afternoon, some linking arms to form human chains, in defiance of a decision to ban face masks at public gatherings only the day before.

They chanted a new demand, adding to a list of five demands reiterated over more than four months of protest: "We have the right to wear face masks."

Hong Kong's embattled chief executive, Carrie Lam, says she is invoking emergency powers to ban face masks during public assemblies starting at midnight Friday (12 p.m. ET).

The ban on face masks is an attempt to quell increasingly violent anti-government protests that have racked the city for more than 17 weeks.

"One thing is certain. If lawbreakers are not wearing masks, it is much easier for us to prove the charges and bring them to courts," said Hong Kong's security secretary, John Lee Ka-chiu, at a last-minute news conference held to announce the ban in Hong Kong.

Updated at 7 a.m. ET

Near Beijing's center, along Chang'an Avenue — the Avenue of Eternal Peace — more than 100,000 performers and soldiers readied for a mass military parade that would unveil China's newest fighting technology, including a hypersonic missile and stealth fighter jets.

At promptly 10 a.m. Tuesday, the parade began with 70 rounds of cannon fire.

Major streets have been cordoned off for hours at a time, leaving restaurant and bar customers stranded overnight. Bomb-sniffing dogs stand guard on busy corners. Teams of hawk-eyed retirees sporting red armbands patrol the sidewalks as part of volunteer neighborhood watch committees, ready to report the smallest sign of a challenge to public security.

Gold-domed mosques and gleaming minarets once broke the monotony of the Ningxia region's vast scrubland every few miles. This countryside here is home to some of China's 10.5 million Hui Muslims, who have practiced Sunni or Sufi forms of Islam within tight-knit communities for centuries, mainly in the northwest and central plains. Concentrated in the Ningxia region, the Hui are China's third-largest ethnic minority.

The Trump administration has shown unwavering support for the Israeli government, except for one major criticism: China's growing influence in the Israeli economy.

Chinese companies have invested in strategic Israeli infrastructure, from shipping to electricity to public transportation, and they have bought up millions of dollars in stakes in cutting-edge technology startups.

Where Israel sees an opportunity to access the world's second-largest economy, the United States sees security threats posed by its main adversary.

Cheng Hao is struggling to understand why his younger brother was arrested.

The 50-year-old retiree and occasional deliveryman says he was living a quiet, unremarkable existence in China's eastern port city of Nanjing. He had only seen his brother sporadically and never took much interest in his advocacy work, he says.

That is until July 24, when he heard that the authorities arrested his younger brother Cheng Yuan, a public interest advocate, two days before and took him into custody in the city of Changsha.

Hong Kong's embattled chief executive, Carrie Lam, is officially withdrawing an extradition bill with China after more than three months of sometimes violent protest.

In a videotaped speech, Lam cited growing clashes between protesters and police and online harassment from both sides as an impetus for backing down regarding the bill.

"For many people, Hong Kong has become an unfamiliar place," Lam said. "We need a common basis to start such a dialogue."

Updated at 5:40 a.m. ET

Joshua Wong, Hong Kong's most famous pro-democracy leader, was arrested on Friday along with fellow activists and politicians in what appeared to be a coordinated sweep by the city's police ahead of a mass anti-government march that had been planned for the weekend.

Updated on Sept. 19 at 10:23 a.m. ET

The popular Chinese messaging app WeChat is Zhou Fengsuo's most reliable communication link to China.

That's because he hasn't been back in over two decades. Zhou, a human rights activist, had been a university student in 1989, when the pro-democracy protests broke out in Beijing's Tiananmen Square. After a year in jail and another in political reeducation, he moved to the United States in 1995.

When the White House decided to levy tariffs on goods from China, U.S. leaders were divided on whether a prolonged trade dispute was a wise course of action.

Now, so is Beijing.

Earlier this month, Chinese state media launched a domestic blitz depicting the Hong Kong protests as riots funded by the CIA. China-linked social media accounts then flooded Twitter and Facebook with thousands of pro-Beijing posts and targeted advertisements.

Social media companies are now pushing back.

As anti-Beijing protests in Hong Kong enter their third month, China's leaders face a new challenge: managing perceptions of the protests at home.

China is anxious the protests might inspire similar dissent on the mainland, where huge swathes of territory — including the regions of Xinjiang and Tibet — have also seen numerous instances of opposition to Beijing's governance.

When hundreds of thousands filled Hong Kong's streets on June 9 to protest a controversial extradition bill, the only mainland coverage came from China Daily, an English-language state newspaper geared towards overseas audiences.

It falsely labelled the march as one in support of the bill, which would allow extradition of some criminal defendants in Hong Kong to face trial in China. The state broadcaster, CCTV, kept its coverage to a minimum. China's government was silent.

Last Monday, China let the yuan drop to its lowest value since 2008. The currency is now trading at just over 7 yuan to the dollar.

Later that day, the U.S. Treasury Department promptly labeled China a "currency manipulator."

In 1978, President Jimmy Carter received a late-night call from Beijing. It was from his science adviser saying Chinese leader Deng Xiaoping wanted to send 5,000 students to the United States. "Tell him to send 100,000," Carter recalls parrying back.

Amid weeks of mass anti-government demonstrations in Hong Kong that have frequently turned violent, Beijing on Tuesday issued a stark warning to protesters: "those who play with fire will perish by it."

The remarks, at a news conference in Beijing, were made by Yang Guang, a spokesman for the Hong Kong and Macau Affairs Office of the State Council.

He said China has "tremendous power" to put down the protests and warned that anyone who engages in "violence and crimes ... will be held accountable."

China's yuan plunged to below 7 per U.S. dollar on Monday morning, the lowest valuation for the currency in 11 years.

The slide in value comes as the U.S. and China remain locked in a trade dispute, leading some analysts to surmise that the devaluation is retaliation for additional U.S. tariffs announced on Chinese goods last week.

"The drop suggests that the central bank of China is willing to weaponize the currency in light of the trade war," says Andrew Collier, managing director of Orient Capital Research in Hong Kong.

A sudden knock at one's door. An unexpected call to meet off campus. Surreptitious visits to family members.

When Facebook announced plans in June to launch a new digital currency called Libra, the news sent monetary officials scrambling in China.

That's because since 2014, the People's Bank of China has been looking into building its own, centrally controlled cryptocurrency.

"We will keep a close eye on the new global digital currency," Wang Xin, research director at China's central bank, said of Libra at a conference in early July in Beijing. "We had an early start ... but lots of work is needed to consolidate our lead."

Former Chinese Premier Li Peng, who became known as the "Butcher of Beijing" for playing a major role in the brutal crackdown on the Tiananmen Square student protests in 1989, has died at the age of 90.

China and the United States are locked in a trade fight, a technology race and competing world military strategies. Leaders of these countries seem to be pulling the world's two largest economies apart.

These tensions are especially felt by those living with a foot in each country. The NPR special series A Foot In Two Worlds reveals the stories of people affected because of their ties to both nations. Reports from both the U.S. and China show how deeply and broadly the two nations are connected and what's at stake as they reshape their relations.

A Trump administration decision to restrict the sale of U.S. technology to Chinese telecommunications company Huawei will disrupt global supply chains, say analysts, ramping up pressure on U.S. allies reluctant to join in efforts to shut out Huawei from advanced 5G mobile networks.

For the last 15 years, Addgene has dedicated itself to accelerating medical research. The nonprofit in Watertown, Mass., does so by sharing research materials globally, like chromosomal DNA, used in the search for breakthrough medical cures.

That could soon change.