On defense matters, the Marshall Islands’ strategic value to the United States no longer rests on the Pacific nuclear testing grounds but on Kwajalein, the largest of the Marshall atolls, which is home to the Ronald Reagan Ballistic Missile Defense Test Site. The 1,200 Americans who live on the base launch missiles, operate space weapons programs and track NASA research, supported by an annual budget of $182 million. About 900 Marshallese workers take a ferry to the base every day to support them.

The Pentagon, which has a lease on Kwajalein until 2066, has commissioned scientific studies on the impact that rising sea levels will have on the base’s mission. In 2008, a tidal wash flooded the base and destroyed all the freshwater supplies on the island. The military responded with expensive desalination machines and heavy-duty sea walls made of riprap, a fortified granite used in hydraulic engineering.