India, Nov. 18 -- Private maritime security companies are not new to the Indian Ocean. For years, firms from Europe and the Gulf have offered escort services to protect vessels from piracy. But a new player has entered the field with a very different agenda: China. Through commercial "maritime security companies," many staffed by former PLA veterans, Beijing is quietly building a grey-zone naval presence along Africa's eastern seaboard.

These companies, registered as private escorts or shipping protection outfits, operate in the Gulf of Aden, around the Horn of Africa, and increasingly near Somali waters. Officially, they safeguard Chinese commercial vessels from piracy. Unofficially, they extend China's maritime situational awareness, g...