Indonesia already makes good use of one weapon against the foreign boats that routinely fish illegally in its vast waters: explosives. To discourage the activity—which costs it billions of dollars in lost revenue annually—the archipelago nation has been on a boat-blasting binge in recent years.

Reuters/Jessica Helena A crude weapon.

But explosions only go so far. Now Indonesia is adding a new weapon to its arsenal: nano-satellites. Recently the government signed a memorandum of understanding with San Francisco-based startup Spire Global—a “satellite-powered data company”—to pinpoint the location of illegal fishing vessels trawling its waters.

Spire’s low-cost nano-satellites—they’re about the size of a shoebox and weigh 11 pounds (5 kilograms)—are designed for listening rather than looking (paywall). By analyzing radio waves they can collect data that’s useful in certain areas, including shipping, global trade, and illegal fishing. And because the satellites are networked together and positioned around the globe, they can provide constantly updated data from remote or ocean-covered parts of the planet.

In the case of illegal fishing, the satellites can pick up data from the Automatic Identification System (AIS) transponders that ships are required by international law to use. They can also detect when a ship has turned off the transponder, which could signal it’s planning to enter waters illegally. That would help Indonesia, which has 17,000 islands, know where to best deploy its patrol ships.

Reuters/Beck Diefenbach One of Spire’s tiny satellites.

Combating illegal fishing has been a top priority for Indonesian president Joko Widodo since he came to power in 2014. At the time he noted that (paywall) 90% of the approximately 5,400 fishing vessels operating in the nation’s waters on any given day were illegal.

Many illegal fishing boats come from nearby nations, but China’s aggressive tactics in the South China Sea have Indonesia worried. Beijing claims nearly all of the sea as its own, along with all its vast natural resources, including fish stock. It bases the claim partly on a nine-dash line it drew on a map after World War 2. That line comes close to Indonesia’s remote Natuna islands, northwest of Borneo.

China has acknowledged the islands belong to Indonesia, but Beijing also encourages its distant-water fishing fleet to operate in the exclusive economic zones of other nations, even ones as far away as Argentina. Last month an Indonesia patrol vessel seized a 300-ton Chinese trawler (paywall) and arrested the crew for illegally fishing within its 200-mile exclusive economic zone of the Natunas. As it tried to bring the trawler to base, Chinese coastguard vessels entered the scene. One rammed the trawler free (paywall). Chinese sailors then boarded the trawler and took it back out of Indonesian waters.

Beijing is already known to aggressively back the Chinese fishing fleet through subsidies, logistical support, and diplomatic intervention. With China militarizing and island-building in the South China Sea, that fishing fleet will likely have stronger support in the future—meaning those tiny satellites could prove increasingly useful for Indonesia.