A companion land-based missile is thought to have been developed already.

The systems are based on the now decommissioned Soviet R-27 submarine-launched ballistic missile.

The report, published in the authoritative Jane's Defence Weekly, says the land-based system has an estimated range of 2,500km to 4,000km (1,500 miles to 2,500 miles) while the sea-based system is thought to be capable of hitting a target more than 2,500km away.

"These new land and sea-based systems appreciably expand the ballistic missile threat presented by the DPRK [North Korea]," the report said.

But a more significant part of the new developments appears to be the sea-based missile, as it could be transported almost anywhere in the world by submarine or ship.

Such a system "could finally provide [the North Korean] leadership with something that it has long sought to obtain — the ability to directly threaten the continental US," the report warns.

Ian Kemp, the news editor of Jane's Defence Weekly, said only five other countries have this capability: — the declared nuclear powers of the US, the UK, France, China and Russia.

He told BBC News Online that North Korea was "almost certainly" developing the missile with the intention of adding nuclear warheads.

A Potential Missile Attack from North Korea. In 1998, N. Korea flight-tested its Taepo-dong 1 missile, which could haul a 1,000-kg nuclear bomb about 2,500 kms The same missile might carry a lighter biological or chemical warhead 4,100 kilometers. Alaska's Aleutian Islands and the western end of the Hawaiian Islands lie about 4,500 kilometers away. Taep-dong 2 missile has a range of up to 6,000 kilometers.

Pyongyang could also be intending to sell its new missiles to another country, although according to Jane's, there is no evidence that any attempt has been made so far.

Iran would appear the ideal customer, the Jane's report says, "given its requirement for a system capable of striking Israel from the security of its own territory."

A spokeswoman for the US state department declined to comment specifically on the apparent new threat.

Darla Jordan told BBC News Online simply: "The US will continue to work closely with other like-minded countries to address North Korea's nuclear efforts."

Mystery regime

Information about North Korea's military capabilities is notoriously sketchy, given the ultra-secretive nature of its communist regime.

The US and North Korea remain deadlocked over Pyongyang's controversial nuclear programme, and the isolated Stalinist nation has long been seen as a threat to regional security.

North Korea has already proved it owns short-range missiles such as the Taepodong 1, which is capable of reaching a target up to 2,000km away. A Taepodong 1 was fired over Japanese territory in 1998, landing in the Pacific Ocean and causing much alarm in Tokyo.

Correspondents say there is mounting evidence that Pyongyang has also been working on a missile with a much longer range, the Taepodong 2, which is thought to be capable of reaching targets 8,000km away, such as Hawaii or Alaska.

According to Kemp, there is no evidence that the advent of the new missiles will affect the completion of the Taepodong 2.

The two systems could be complementary, he said.

Country Profile: North Korea

For decades North Korea has been one of the world's most secretive societies. It is one of the few remaining countries still under communist rule.
Hopes that its rigid isolation might have been coming to an end have been scotched by an ongoing nuclear crisis.

North Korea emerged in 1948 amid the chaos following the end of World War II. Its history is dominated by its Great Leader, Kim Il-sung, who shaped political affairs for almost half a century.

OVERVIEW

Map of North Korean missile sites

After the Korean War, Kim Il-sung introduced the personal philosophy of Juche, or self-reliance, which became a guiding light for North Korea's development. But decades of this rigid state-controlled system have led to stagnation and a leadership dependent on the cult of personality.

Aid agencies have estimated that up to two million people have died since the mid-1990s as a result of acute food shortages caused by natural disasters and economic mismanagement.

Kim Il-sung's son, Kim Jong-il, is now head of state, but the post of president has been assigned "eternally" to his late father. Pyongyang has accused successive South Korean governments of being US "puppets," but South Korean President Kim Dae-jung's visit in 2000 signalled a thaw in relations. Seoul's "sunshine policy" towards the north aimed to encourage change through dialogue and aid.

In 2002 US President George W Bush named North Korea as part of an "axis of evil"; the country is said to have a handful of nuclear weapons and a uranium-enrichment programme.

A thaw in relations with Seoul and a tentative reaching-out to the world were dealt a blow in late 2002 by Pyongyang's decision to reactivate a nuclear reactor and to expel international inspectors.

HISTORY

Tangun, national founder

The ancient history of the Korean peninsula can be traced to the Neolithic Age, when Turkic-Manchurian-Mongol peoples migrated into the region from China. The first agriculturally based settlements appeared around 6000 B.C. Some of the larger communities of this era were established along the Han-gang River near modern-day Seoul, others near Pyongyang and Pusan. According to ancient lore, Korea's earliest civilization, known as Choson, was founded in 2333 B.C. by Tan-gun.

In the 17th century, Korea became a vassal state of China and was cut off from outside contact until the Sino-Japanese War of 1894–1895. Following Japan's victory, Korea was granted independence. By 1910, Korea had been annexed by Japan, which developed the country but never won over the Korean nationalists, who continued to agitate for independence.

After Japan's surrender at the conclusion of World War II, the Korean peninsula was partitioned into two occupation zones, divided at the 38th parallel. The USSR controlled the north, with the U.S. taking charge of the south. In 1948, the division was made permanent with the establishment of the separate regimes of North and South Korea. The Democratic People's Republic of Korea (North Korea) was established on May 1, 1948, with Kim Il Sung as president.

Hoping to unify the Koreas under a single Communist government, the North launched a surprise invasion of South Korea on June 25, 1950. In the following days, the UN Security Council condemned the attack and demanded an immediate withdrawal.

Korean War (1050-53)

President Harry S. Truman ordered U.S. air and naval units into action to enforce the UN order. The British government followed suit, and soon a UN multinational command was set up to aid the South Koreans.

The North Korean invaders swiftly seized Seoul and surrounded the allied forces in the peninsula's southeast corner near Pusan. In a desperate bid to reverse the military situation, UN Commander Gen. Douglas MacArthur ordered an amphibious landing at Inchon on Sept. 15 and routed the North Korean army. MacArthur's forces pushed north across the 38th parallel, approaching the Yalu River.

Prompted by this successful counteroffensive, Communist China entered the war, forcing the UN troops into a headlong retreat. Seoul was lost again, then regained. Ultimately, the war stabilized near the 38th parallel, but dragged on for two years while negotiations took place. An armistice was agreed to on July 27, 1953.

General MacArthur and staff viewing the Inchon landings, September 1950

By early 1994, tensions had mounted over international inspection of North Korea's nuclear sites. Kim Il Sung's death on July 8, 1994, introduced a period of uncertainty, as his son, Kim Jong Il, assumed the leadership mantle. Negotiations over the country's suspected atomic weapons dragged on, but an agreement was reached in June 1995 that included a provision for providing the North with a South Korean nuclear reactor.

The nuclear crises that characterized the mid-1990s were overshadowed when famine struck the nation's 24 million inhabitants in 1998 and 1999. Two years of floods were followed by severe droughts in 1997 and 1998, causing devastating crop failures. Because of lack of fuel and machinery parts, and weather conditions that have encouraged parasites, only 10% of North Korea's rice fields could be worked. Despite the staggering food crisis that necessitated foreign aid, North Korea remains one of the world's few remaining hermetic hard-line Communist regimes.

In Sept. 1998, North Korea launched a test missile over Japan, claiming it was simply a scientific satellite. This launch alarmed Japan, and much of the rest of the world, about North Korea's intentions regarding reentry into the nuclear arms race.

In 1999, North Korea agreed to allow the United States to conduct ongoing inspections of a suspected nuclear development site, Kumchangri, which North Korea admitted had been devised for "a sensitive military purpose." In exchange, the U.S. would increase food aid and initiate a program for bringing potato production to the country.

Antagonism between North and South Korea erupted into open aggression twice within six months in late 1998 and 1999, with South Korea hitting one North Korean vessel and sinking two others that were discovered trespassing in South Korean waters.

In the fall of 1999, North Korea's four years of severe famine, which claimed an estimated 2 million to 3 million lives between 1995 and 1998, had begun to wane.

Kim Jong-Il (left) greets Kim Dae-Jung, who visited Pyongyang for the historic South-North Summit.

Tension with South Korea eased dramatically in June 2000, when South Korea's president, Kim Dae Jung, met with North Korea's President Kim Jong Il in Pyongyang. The summit marked the first ever meeting of the two countries' leaders. But efforts toward reconciliation fizzled thereafter, and various minor military skirmishes followed over the next years.

In Jan. 2002, President Bush described North Korea as part of an "axis of evil." Such open hostility marked a dramatic shift in U.S. policy toward North Korea from the Clinton administration's policy of engagement.

In July 2002, North Korea began a series of radical economic initiatives aimed at reforming the devastated economy and introducing free-market policies. The country devalued its currency, raised food prices by as much as 50%, and increased wages.

The reclusive and secretive North Korea stunned the world in late 2002 with two shocking admissions. In September, the government unexpectedly acknowledged that it had kidnapped about a dozen Japanese in the 1970s and 1980s for the purposes of training North Korean spies. In October, confronted with U.S. intelligence, North Korea admitted that it had violated a 1994 agreement freezing its nuclear-weapons program and had in fact been developing nuclear bombs.

In late December, North Korea expelled UN weapons inspectors from the country and announced it could no longer agree to the terms of the nuclear Non-Proliferation Treaty (NPT), officially withdrawing from it in January 2003. Kim continued to provoke the international community into the spring, reactivating a plant at Yongbyon that converts nuclear waste into weapons-grade plutonium, test-launching missiles, and taunting the U.S. by intercepting an air force spy plane.

During talks with China and the U.S. in April, North Korea announced that it had already produced nuclear weapons and threatened to test or export them. In July North Korean officials reported that the country had reprocessed enough plutonium to build six nuclear bombs. Kim's motives for this bellicose stance have mystified much of the world, but in the past Kim has regularly confused diplomacy with extortion, using threats and hostile acts to wring aid and food from the international community for his starving, impoverished country. It was difficult to decipher how Kim expected to accomplish his aims — economic aid and a safeguard against U.S. attack — through such reckless brinkmanship.

Satellite photos of Yongbyon nuclear site

Refusing to bow to North Korea's mercurial demands, the United States informed the nation's diplomats that it would not begin to negotiate until North Korea first dismantled its nuclear program. China took on the role of mediator between North Korea and the U.S., urging less inflexibility on both sides. A modest breakthrough occurred when officials from the U.S., North Korea, China, Russia, South Korea, and Japan met in August in Beijing, although nothing substantive resulted. Another round of six-nation negotiations in Feb. 2004 were also inconclusive.

The International Atomic Energy Agency announced in May 2004 that is has strong evidence that North Korea supplied Libya with about two tons of uranium. If the allegation is true, it would indicate that North Korea has moved beyond selling missiles and missile technology.

A massive explosion rocked Ryongchon, a city northwest of the capital, Pyongyang, in April 2004. Initial reports indicated the explosion was caused by the collision of two trains carrying fuel, but officials later said the blast was set off when a train car carrying explosives touched a live power cable. Hundreds were feared dead. The normally insular North Korean government asked the United Nations for help in dealing with the aftermath of the tragedy.

At the third round of negotiations on North Korea's nuclear weapons program in June 2004, the U.S. offered North Korea the delivery of heavy fuel oil and a "provisional security guarantee" if it agrees to disclose details of its weapons program, allow inspections, and begin to dismantle its nuclear program within three months. North Korea did not respond to the offer. Instead, the country's negotiator threatened to test one of its nuclear weapons.

FACTS