Image copyright AP Image caption Four recent North Korean missile launches - such as this one last month - are said to have failed 
 
 North Korea has test-fired two mid-range ballistic missiles from its eastern coast, says South Korea. 
 
 The first launch was considered to have failed, travelling about 150km (90 miles) before landing in the sea. 
 
 But the second, launched hours later, flew about 400km and reached an altitude of 1,000km, the most effective test to date. 
 
 A confirmed successful test would mark a step forward for North Korea after four failed launches in recent months. 
 
 Both launches are believed to have been intermediate-range Musudan missiles. 
 
 South Korea's Joint Chiefs of Staff said Seoul and the US were "carrying out an in-depth analysis" of the second missile, and did not say whether it was considered a success. 
 
 North Korea, which is developing nuclear weapons, is banned by UN resolutions from any use of ballistic missile technology. 
 
 In January it conducted its fourth nuclear test, claiming it to be its first using a hydrogen bomb. Shortly after that Pyongyang launched a satellite, widely seen as a test of long-range missile technology. 
 
 South Korea has held a national security meeting to discuss Wednesday's missile launches, the Yonhap news agency reported. 
 
 Analysis: Stephen Evans, BBC News, Seoul 
 
 Image copyright EPA Image caption North Korea has never conducted a full flight test of a Musudan missile 
 
 North Korea has tested these medium-range missiles four times now in three months and twice on Wednesday. Outside experts and intelligence agencies believe the first five launches were certainly failures, but aren't sure about the sixth. 
 
 It seems to have gone about 400km, far short of its maximum range. That may be because it failed or it may be because a decision was taken not to send it over Japan which had said it would shoot any missile down. 
 
 So why is North Korea conducting tests so frequently? 
 
 Some Western scientists say that the more conventional way of testing is to conduct the test, and if it fails, to go away and work out why before trying again some months or even a year later. 
 
 If this steady method over a long period isn't being followed by North Korea, it may be because of intense pressure from the top, a pressure the scientists on the ground will no doubt feel. 
 
 'Provocative actions' 
 
 The US State Department has strongly condemned the launches, with spokesman John Kirby saying they would only increase international efforts to stop North Korea's weapons programme. 
 
 "We intend to raise our concerns at the UN to bolster international resolve in holding [North Korea] accountable for these provocative actions," said Mr Kirby in a statement. 
 
 North American Defense Command (Norad), which tracked the missiles, determined they did not pose a threat to North American territories. 
 
 Image copyright Reuters Image caption South Korea's presidential office has announced that it would hold a national security meeting to discuss the launch 
 
 Nato Secretary General Jens Stoltenberg said the launches "undermine international security and dialogue". 
 
 Japanese Prime Minister Shinzo Abe has said such tests "clearly cannot be tolerated". 
 
 The Musudan is believed to have a range of about 3,000km - far enough for it to hit South Korea, Japan and the US territory of Guam in the Western Pacific. 
 
 North Korea is thought to have dozens of Musudans but has never conducted a full-distance test. 
 
 The four other missiles tested in the last two months either exploded mid-air or crashed. 
 
 Surrounding countries had detected preparations for a launch in the past few days and warned that it was about to happen. 
 
 The Musudan missile 
 
 The Musudan, also known as the Nodong-B or the Taepodong-X is an intermediate-range ballistic missile. 
 
 Estimates differ dramatically on its range, with Israeli intelligence putting it at 2,500km and the US Missile Defense Agency estimating about 3,200km. Other sources put its upper limit at 4,000km. 
 
 The lower range of the Musudan will enable it to hit the whole of South Korea and Japan. At its upper range it would be able to target US military bases on Guam. ||||| The U.N. Security Council met late Wednesday in an emergency session to discuss North Korea's latest missile tests, which violate U.N. resolutions. 
 
 The United States and Japan called the meeting, in consultation with their ally, South Korea, to deal with what U.S. Ambassador Samantha Power called "a pattern of defiance" by Pyongyang. 
 
 "The tests in the last 24 hours are just the latest in that pattern," Power told reporters on her way into the session. "Since March 2 and the passage of Resolution 2270, we have seen 10 ballistic missile tests — a rapid series of these tests in defiance of five U.N. Security Council resolutions. That is unacceptable." 
 
 Power urged the council to promptly condemn North Korea. 
 
 Following the hourlong closed meeting, council president Alexis Lamek said there was a "very large convergence of views" that the launches violate all council resolutions. Lamek, the French deputy ambassador, said he expects a statement from the council "within days." 
 
 It is not unusual for the 15-nation council to take several days, if not weeks, to respond to North Korea following ballistic missile launches and nuclear tests. 
 
 In March, the council adopted resolution 2270, which imposed tough new sanctions on Pyongyang for conducting its fourth nuclear test and launching a long-range rocket. The sanctions include suspending currency transfers and restricting the North's lucrative mineral trade that had accounted for more than half of the country's $2.5 billion in exports to China alone. 
 
 "The provisions of 2270 are completely unprecedented," Power said. She urged council members to address any "hidden gaps" in the enforcement of those measures. 
 
 North making progress 
 
 Pyongyang conducted its fifth and sixth test of the intermediate-range Musudan missile on Wednesday from the coastal city of Wonsan. U.S. and South Korean military officials said the first missile failed shortly after it was launched but the second missile flew approximately 400 kilometers before falling into the Sea of Japan or East Sea as it called in South Korea. 
 
 The last missile tested did not reach the 3,000-kilometer distance the Musudan is designed for, to potentially reach U.S. military bases in Asia and the Pacific. It apparently also did not demonstrate the atmospheric re-entry capability needed to accurately hit a target. But analysts said North Korea continues to learn from each failure and is making advancements with each new test. 
 
 
 
 WATCH: Pyongyang's nuclear test 
 
 “This is a very important milestone because the previous launches had blown up either very shortly after launch or possibly even right at launch. So this is a real sign of progress,” said Jeffrey Lewis, the director of the East Asia Nonproliferation Program at the Middlebury Institute of International Studies in California. 
 
 The multiple missile tests, Lewis said, also indicates that international sanctions have so far not affected North Korea’s ability to acquire the material and technology needed to manufacture these weapons. 
 
 According to South Korean media, North Korea is believed to have up to 30 Musudan missiles, which officials said were first deployed around 2007. The first Musudan test occurred in April of this year. 
 
 World condemns Kim 
 
 In Washington, White House spokesman Josh Earnest said the U.S. "strongly condemns the provocative actions that are in violation of international law." "The U.S. will do what we have done in the past, work with international allies and others like Russia and China about what pressure can continue to be applied," he said. 
 
 French Ambassador Francois Delattre, who is president of the U.N. Security Council this month, said the latest tests are a "clear violation" of Security Council resolutions that ban North Korea from using ballistic missile technology and developing nuclear weapons. 
 
 "The North Korean ballistic missile program is a serious threat to regional and international peace and security. Confronted with the threat of proliferation we consider that weakness is not an option. Based on all this, we favor a quick and firm (Security Council) reaction," he said. 
 
 The United Nations imposed tough new sanctions on North in March for conducting its fourth nuclear test and launching a long-range rocket. The sanctions include suspending currency transfers and restricting the North’s lucrative mineral trade that had accounted for over half of the country’s $2.5 billion in exports to China alone. 
 
 Kim Jong Un has declared his country a nuclear state and has defiantly responded to the international sanctions by conducting multiple missile tests and threatening to proceed with further nuclear testing. 
 
 Japan's Self Defense Forces have been on high alert with anti-missile launchers stationed around the country in case the North Korean missiles entered its airspace. 
 
 Tokyo said it would issue a strong protest against North Korea for its latest violation of United Nations resolutions. 
 
 South Korea called the missile test a clear provocation “against us” and urged Pyongyang to exercise restraint. 
 
 “I would like to advise them that it will be good for North Korea to put more effort into peace on the Korean peninsula and their people's livelihood, which the North has been consistently saying," said South Korean Unification Ministry spokesman Jeong Joon-hee. 
 
 Regional security conference 
 
 North Korea’s latest missile test will likely be addressed at a closed-door regional security forum currently underway in Beijing that includes diplomats from North Korea, the U.S. and South Korea. At the conference, North Korean envoy Choe Son Hui is expected to defend her country’s right to develop nuclear weapons to protect itself against the perceived threat from the United States. 
 
 Even though China is North Korea’s key ally and trading partner, Beijing opposes Pyongyang’s nuclear program and supports the most recent U.N. sanctions imposed on North Korea. However critics said enforcement has been lax as China does not want to destabilize the Kim Jong Un government, and it is unlikely Beijing will support any further measures that would weaken its ally. 
 
 “Considering the current situation in Northeast Asia, it is not easy for China to impose sanctions against North Korea as North Korea can be a card for China,” said Korea analyst Woo Su-keun with Donghua University in Shanghai. 
 
 Chinese President Xi Jinping recently met with high-level North Korean party officials in Beijing to bolster ties that have been frayed by the North’s nuclear provocations. 
 
 Xi has called for restarting international talks to convince the North to give up its nuclear program for economic aid and security guarantees. 
 
 Washington and its allies demand that North Korea first halt any further nuclear development before new talks can take place. ||||| SEOUL/TOKYO (Reuters) - North Korea launched what appeared to be an intermediate-range missile on Wednesday to a high altitude in the direction of Japan before it plunged into the sea, military officials said, a technological advance for the isolated state after several test failures. 
 
 The launch came about two hours after a similar test failed, South Korea’s military said, and covered 400 km (250 miles), more than halfway towards the southwest coast of Japan’s main island of Honshu. 
 
 The launches and earlier nuclear tests show continued defiance of international warnings and a series of U.N. Security Council resolutions and sanctions, which North Korea rejects as an infringement of its sovereignty. 
 
 Japanese Defence Minister Gen Nakatani said the second missile reached an altitude of 1,000 km (620 miles), indicating North Korea had made progress. 
 
 “We don’t know whether it counts as a success, but North Korea has shown some capability with IRBMs (intermediate range ballistic missiles),” he told reporters in Tokyo. 
 
 “The threat to Japan is intensifying.” 
 
 Reclusive North Korea and the rich, democratic South are technically still at war because their 1950-53 conflict ended in an armistice, not a peace treaty. The North regularly threatens to destroy the Japan, South Korea and the South’s main ally, the United States. 
 
 South Korean President Park Geun-hye denounced the test. 
 
 “The North Korean regime must realize that complete isolation and self-destruction await at the end of reckless provocation,” she said. 
 
 NATO Secretary General Jens Stoltenberg also decried North Korea’s “provocative actions”. 
 
 “I strongly condemn the launch by North Korea of two ballistic missiles,” Stoltenberg said in a statement. 
 
 “These repeated provocative actions ... undermine international security and dialogue,” he said, calling for North Korea to “fully comply with its obligations under international law, not to threaten with or conduct any launches using ballistic missile technology and to refrain from any further provocative actions”. 
 
 The first missile was launched from the east coast city of Wonsan, a South Korean official said, the same area where previous tests of intermediate-range missiles were conducted, possibly using mobile launchers. 
 
 FIFTH STRAIGHT FAILURE 
 
 South Korea’s Yonhap news agency, quoting a government official, said the first missile disintegrated mid-air after a flight of about 150 km (95 miles). 
 
 Wednesday’s first launch was the fifth straight unsuccessful attempt in the past two months to launch a missile that is designed to fly more than 3,000 km (1,800 miles) and could theoretically reach any part of Japan and the U.S. territory of Guam. 
 
 Jeffrey Lewis, of the California-based Middlebury Institute of International Studies, said missiles were usually fired at a certain angle to maximize range, so the high altitude of the second launch may have been chosen to avoid Japanese airspace. 
 
 “That suggests the missile worked perfectly,” Lewis said. “Had it been fired at its normal angle, it would have flown to its full range.” 
 
 North Korean leader Kim Jong Un looks at a rocket warhead tip after a simulated test of atmospheric re-entry of a ballistic missile, at an unidentified location in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on March 15, 2016. REUTERS/KCNA 
 
 Lewis said failures were a normal part of testing and that North Korea would fix problems with the Musudan intermediate-range missile sooner or later. 
 
 “If North Korea continues testing, eventually its missileers will use the same technology in a missile that can threaten the United States,” Lewis told Reuters. 
 
 Nakatani said North Korea’s repeated missile launches were a “serious provocation” and could not be tolerated. 
 
 Japan indicated after the first launch that it would protest strongly because it violated U.N. resolutions, even though the launches posed no immediate threat to Japanese security. 
 
 In Seoul, South Korea’s presidential office said a national security meeting was convened to discuss the latest missile launches. 
 
 LONGER-RANGE ROCKETS 
 
 The U.S. military detected the two missiles, most likely Musudan, from North Korea, the U.S. military’s Pacific Command said. A Pentagon spokesman said both missiles fell into the Sea of Japan. North Korea is believed to have up to 30 Musudan missiles, according to South Korean media, which officials said were first deployed around 2007, although the North had never attempted to test-fire them until April. 
 
 While North Korea has developed potential longer-range rockets, such as its 30-metre (98 ft) Unha-3, a home-grown three-stage rocket based on 1950s Soviet Scud missile technology, it needs to be fueled from a fixed launch pad making it easy to detect and impractical as a weapon. 
 
 A smaller, powerful intermediate missile that is easier to deploy on a mobile launcher poses a harder threat to counter. 
 
 The U.N. Security Council, backed by the North’s main diplomatic ally, China, imposed tough new sanctions in March after North Korea conducted its fourth nuclear test in January and launched a long-range rocket that put an object into space orbit. 
 
 Slideshow (7 Images) 
 
 “At present, the situation on the peninsula remains very complex and severe. We think that the relevant party should avoid doing anything to further worsen tensions,” Chinese Foreign Ministry spokeswoman Hua Chunying told reporters at a regular press briefing on Wednesday. 
 
 North Korea has conducted a series of tests since then that it claimed showed progress in nuclear weapons and long-range ballistic missile capabilities, including new rocket engines and simulated atmospheric re-entry.
– North Korea is not only continuing to defy international warnings to stop testing ballistic missiles, it's starting to get pretty good at launching them. Relatively speaking, anyway: Pyongyang launched two intermediate-range Musudan missiles in the direction of Japan on Wednesday, reports the BBC. The first one flopped almost immediately, just like four previous launches. But the second one reached an altitude of about 620 miles before plunging into the sea, raising concern in both South Korea and Japan, reports Reuters. The missile also covered about 250 miles, getting more than halfway to Japan's coast. The BBC notes the missile's range is much further; it's unclear whether it fell short due to failure or was intentionally kept from reaching Japan. "This is a very important milestone because the previous launches had blown up either very shortly after launch or possibly even right at launch," an analyst at the Middlebury Institute of International Studies in California tells the Voice of America. "So this is a real sign of progress." Japan's defense chief put it more succinctly: "The threat to Japan is intensifying." South Korea and the US are still assessing the test, but South Korean President Park Geun-hye denounced the "reckless provocation." UN resolutions forbid the North from working on ballistic missile technology, notes the BBC, but the launches suggest that Pyongyang is having little trouble obtaining the technology and the know-how.