Marshall Islands profile
The Marshall Islands consist of two chains of coral atolls, together with more than 1,000 islets, just north of the Equator.
The atolls are coral deposits on the crater rims of submerged volcanoes.
The islands were occupied by the US for several decades after World War II. They are now a sovereign nation under a Compact of Free Association with the US.
The compact came into force in 1986 and was renegotiated in 2003. The US controls the security and defence of the islands, which receive millions of dollars in aid every year.
Missile tests on Kwajalein atoll
The Kwajalein atoll is used as a missile test range by the United States
Country profiles compiled by BBC Monitoring
Under the compact, the US pays an annual rent to use the Kwajalein atoll as a base and missile test range.
The legacy of the post-war US occupation is seen particularly starkly on Bikini and Enewetak, which were both used for nuclear weapons testing between 1946 and 1958.
The US paid $150 million in a compensation package for the test victims in the 1980s.
But whilst Enewetak has been partly decontaminated, Bikini is still uninhabitable. The Marshall Islands has petitioned for additional compensation.
A major problem for the islands is how to gain some measure of financial independence from the US. Imports dwarf exports, unemployment is high and many islanders live by subsistence farming.
Tourism is one option; unspoiled beaches abound and the islands are an ideal base for scuba diving and sports fishing.
The islands also sell fishing rights to other countries, and offer ship registrations under the Marshall Islands flag.