Marshall Islands in the context of Rongelap Atoll

Micronesia (UK: /ˌmaɪkrəˈniːziə/, US: /-ˈniːʒə/ ) is a subregion of Oceania, consisting of approximately 2,000 small islands in the Northwestern Pacific Ocean. It has a close shared cultural history with three other island regions: Maritime Southeast Asia to the west, Polynesia to the east, and Melanesia to the south—as well as with the wider community of Austronesian peoples.

The region has a tropical marine climate and is part of the Oceanian realm. It includes four main archipelagos—the Caroline Islands, the Gilbert Islands, the Mariana Islands, and the Marshall Islands — as well as numerous islands that are not part of any archipelago.

The Federated States of Micronesia (/ˌmaɪkroʊˈniːʒə/ , abbreviated FSM), or simply Micronesia, is an island country in Micronesia, a region of Oceania. The federation encompasses the majority of the Caroline Islands (excluding Palau) and consists of four states—from west to east: Yap, Chuuk, Pohnpei, and Kosrae—that span the western Pacific just north of the equator for a longitudinal distance of almost 2,700 km (1,700 mi). Together, the states comprise around 607 islands and a combined land area of approximately 702 km or 271 sq mi.

The entire island nation lies across the northern Pacific accordingly: northeast of Indonesia and Papua New Guinea, south of Guam and the Marianas, west of Nauru and the Marshall Islands, east of Palau and the Philippines, about 2,900 km (1,800 mi) north of eastern Australia, 3,400 km (2,100 mi) southeast of Japan, and some 4,000 km (2,485 mi) southwest of Honolulu of the Hawaiian Islands.

Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Over 2,000 nuclear weapons tests have been carried out since 1945. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Because of their destruction and fallout, testing has seen opposition by civilians as well as governments, with international bans having been agreed on. Thousands of tests have been performed, with most in the second half of the 20th century.

The first nuclear device was detonated as a test by the United States at the Trinity site in New Mexico on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of an engineered device, codenamed Ivy Mike, was tested at the Enewetak Atoll in the Marshall Islands on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at Novaya Zemlya on October 30, 1961, with the largest yield ever seen, an estimated 50–58 megatons.

The following is a list of countries and territories where English is an official language used in citizen interactions with government officials. As of 2025, there are 58 sovereign states and 28 non-sovereign entities where English is an official language. Many administrative divisions have declared English an official language at the local or regional level.

Most states where English is an official language are former territories of the British Empire. Exceptions include Rwanda and Burundi, which were formerly German and then Belgian colonies; Cameroon, where only part of the country was under the British mandate; and Liberia, the Philippines, the Federated States of Micronesia, the Marshall Islands, and Palau, which were American territories. English is the sole official language of the Commonwealth of Nations and of the Association of Southeast Asian Nations (ASEAN). English is one of the official languages of the United Nations, the European Union, the African Union, the Organisation of Islamic Cooperation, the Caribbean Community, the Union of South American Nations, and many other international organisations.

The Micronesians or Micronesian peoples are various closely related ethnic groups native to Micronesia, a region of Oceania in the Pacific Ocean. They are a part of the Austronesian ethnolinguistic group, which has an Urheimat in Taiwan.

Ethno-linguistic groups classified as Micronesian include the Carolinians (Northern Mariana Islands), Chamorros (Guam & Northern Mariana Islands), Chuukese, Mortlockese, Namonuito, Paafang, Puluwat and Pollapese (Chuuk), I-Kiribati (Kiribati), Kosraeans (Kosrae), Marshallese (Marshall Islands), Nauruans (Nauru), Palauan, Sonsorolese, and Hatohobei (Palau), Pohnpeians, Pingelapese, Ngatikese, Mwokilese (Pohnpei), and Yapese, Ulithian, Woleian, Satawalese (Yap).

The Compacts of Free Association (COFA) are international agreements establishing and governing the relationships of free association between the United States and the three Pacific Island sovereign states of the Federated States of Micronesia (FSM), the Republic of the Marshall Islands (RMI), and the Republic of Palau. As a result, these countries are sometimes known as the Freely Associated States (FASs). All three agreements next expire in 2043.

These countries, together with the Commonwealth of the Northern Mariana Islands, formerly constituted the Trust Territory of the Pacific Islands, a United Nations trusteeship administered by the United States Navy from 1947 to 1951, and by the U.S. Department of the Interior from 1951 to 1986 (to 1994 for Palau).

The crab claw sail is a fore-and-aft triangular sail with spars along upper and lower edges. The crab claw sail was first developed by the Austronesian peoples by at least 2000 BCE. It is sometimes known as the Oceanic lateen or the Oceanic sprit, even though it is not restricted to Oceania, is neither a lateen sail nor a spritsail, and has an independent older origin.

German New Guinea (German: Deutsch-Neuguinea) consisted of the northeastern part of the island of New Guinea and several nearby island groups, and was part of the German colonial empire. The mainland part of the territory, called Kaiser-Wilhelmsland, became a German protectorate in 1884. Other island groups were added subsequently. The Bismarck Archipelago (New Britain, New Ireland and several smaller islands), and the North Solomon Islands were declared a German protectorate in 1885. The Caroline Islands, Palau, and the Mariana Islands (except for Guam) were bought from Spain in 1899. German New Guinea annexed the formerly separate German Protectorate of Marshall Islands, which also included Nauru, in 1906. German Samoa, though part of the German colonial empire, was not part of German New Guinea.

Following the outbreak of World War I in 1914, Kaiser-Wilhelmsland and nearby islands fell to Australian forces, while Japan occupied most of the remaining German possessions in the Pacific. The mainland part of German New Guinea (Kaiser-Wilhelmsland), the Bismarck Archipelago and the North Solomon Islands are now part of Papua New Guinea. The Northern Mariana Islands are an unincorporated territory of the United States. The Carolines (as the Federated States of Micronesia), the Marshall Islands, Nauru and Palau are independent countries.

Wake Island (Marshallese: Ānen Kio, lit. 'island of the kio flower'), also known as Wake Atoll (Chamorro: Islan Wake), is a coral atoll in the Micronesia subregion of the Pacific Ocean. The atoll is composed of three islets – Wake, Wilkes, and Peale Islands – surrounding a lagoon encircled by a coral reef. The nearest inhabited island is Utirik Atoll in the Marshall Islands, located 592 miles (953 kilometers) to the southeast.

The island may have been found by prehistoric Austronesian mariners before its first recorded discovery by Álvaro de Mendaña de Neira in 1568. Ships continued visiting the area in the following centuries, but the island remained undeveloped until the United States claimed it in 1899. Significant development of the island did not begin until 1935 when Pan American Airways constructed an airfield and hotel, establishing Wake Island as a stopover for trans-Pacific flying boat routes. In December 1941 at the opening of the Pacific Theatre of World War II Japan seized the island, which remained under Japanese occupation until the end of the war in September 1945. In 1972, Pan American Airways ceased using the island for trans-Pacific layovers, instead using Boeing 747 aircraft, which could cross the ocean without stopping. With the withdrawal of Pan American Airways, the island's administration was taken over by the United States Air Force, which later used the atoll as a processing location for Vietnamese refugees during Operation New Life in 1975.

USS Iowa (BB-61) is a retired battleship, the lead ship of her class, and the fourth in the United States Navy to be named after the state of Iowa. Owing to the cancellation of the Montana-class battleships, Iowa is the last lead ship of any class of United States battleships and was the only ship of her class to serve in the Atlantic Ocean during World War II.

During World War II, she carried President Franklin D. Roosevelt across the Atlantic to Mers El Kébir, Algeria, en route to a conference of vital importance in 1943 in Tehran with Prime Minister Winston Churchill of the United Kingdom and Joseph Stalin, leader of the Soviet Union. When transferred to the Pacific Fleet in 1944, Iowa shelled beachheads at Kwajalein and Eniwetok in advance of Allied amphibious landings and screened aircraft carriers operating in the Marshall Islands. She also served as the Third Fleet flagship, flying Admiral William F. Halsey's flag at the Japanese surrender in Tokyo Bay.

Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of Operation Castle. Detonated on 1 March 1954, the device remains the most powerful nuclear device ever detonated by the United States and the first lithium deuteride-fueled thermonuclear weapon tested using the Teller–Ulam design. Castle Bravo's yield was 15 megatons of TNT [Mt] (63 PJ), 2.5 times the predicted 6 Mt (25 PJ), due to unforeseen additional reactions involving lithium-7, which led to radioactive contamination in the surrounding area.

Radioactive nuclear fallout, the heaviest of which was in the form of pulverized surface coral from the detonation, fell on residents of Rongelap and Utirik atolls, while the more particulate and gaseous fallout spread around the world. The inhabitants of the islands were evacuated three days later and suffered radiation sickness. Twenty-three crew members of the Japanese fishing vessel Daigo Fukuryū Maru ("Lucky Dragon No. 5") were also contaminated by the heavy fallout, experiencing acute radiation syndrome, including the death six months later of Kuboyama Aikichi, the boat's chief radioman. The blast incited a strong international reaction over atmospheric thermonuclear testing.

Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which a significant fraction of the explosive yield comes from nuclear fusion.Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab in Enewetak Atoll, in the now independent island nation of the Marshall Islands, as part of Operation Ivy. It was the first full test of the Teller–Ulam design, a staged fusion device.

Due to its physical size and fusion fuel type (cryogenic liquid deuterium), the "Mike" device was not suitable for use as a deliverable weapon. It was intended as a "technically conservative" proof of concept experiment to validate the concepts used for multi-megaton detonations.

Enewetak Atoll (/ɛˈniːwəˌtɔːk, ˌɛnɪˈwiːtɔːk/; also spelled Eniwetok Atoll or sometimes Eniewetok; Marshallese: Ānewetak, [ænʲeːwɛːdˠɑk], or Āne-wātak, [ænʲeːwæːdˠɑk]; known to the Japanese as Brown Atoll or Brown Island; Japanese: ブラウン環礁) is a large coral atoll of 40 islands in the Pacific Ocean and with its 296 people (as of 2021) forms a legislative district of the Ralik Chain of the Marshall Islands. With a land area total less than 5.85 square kilometers (2.26 sq mi), it is no higher than 5 meters (16.4 ft) and surrounds a deep central lagoon, 80 kilometers (50 mi) in circumference. It is the second-westernmost atoll of the Ralik Chain and is 305 kilometers (190 mi) west from Bikini Atoll.

It was held by the Japanese from 1914 until its capture by the United States in February 1944 during World War II, then became Naval Base Eniwetok. Nuclear testing by the US, totaling the equivalent of over 30 megatons of TNT, took place during the Cold War; in 1977–1980, a concrete dome (the Runit Dome) was built on Runit Island to deposit radioactive soil and debris.

The Loaísa expedition was an early 16th-century Spanish voyage of discovery to the Pacific Ocean, commanded by García Jofre de Loaísa [es] (1490 – 20 July 1526) and ordered by King Charles I of Spain to colonize the Spice Islands in the East Indies. The seven-ship fleet sailed from La Coruña, Spain in July 1525 and became the second naval expedition in history to cross the Pacific Ocean, after the Magellan-Elcano circumnavigation. The expedition resulted in the discovery of the Sea of Hoces south of Cape Horn, and the Marshall Islands in the Pacific. One ship ultimately arrived in the Spice Islands in September 1526.