Berlin, July 30 -- For more than a decade, Nguyen Van Cuong, a Vietnamese expat living in Germany, has opened five family-owned apartments in Hanoi's Linh Dam neighbourhood rent-free to the sons and daughters of soldiers stationed on Truong Sa (Spratly). For Cuong, it is a simple gesture of backing those who serve on distant seas.

The story starts more than 30 years ago. Cuong graduated from Hanoi Tourism College and moved to Germany to make a life. In 1996, he and his wife launched a family supermarket in central Berlin. Almost three decades of steady business later, he poured cash into a residential building with about 80 rental units in Linh Dam. He carved out five of those flats, not for income, but for the children of Truong Sa's of...