On paper, it looked like a fantastic deal. In 2017, the Chinese government was offering to spend $100 million to build an ornate Chinese garden at the National Arboretum in Washington DC. Complete with temples, pavilions and a 70-foot white pagoda, the project thrilled local officials, who hoped it would attract thousands of tourists every year. But when US counterintelligence officials began digging into the details, they found numerous red flags. The pagoda, they noted, would have been strategically placed on one of the highest points in Washington DC, just two miles from the US Capitol, a perfect spot for...