Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: Image copyright AFP Image caption The first nuclear test was carried out by the US in the New Mexico desert in 1945 
  
 The apparent hydrogen bomb that North Korea is believed to have detonated underground on Sunday was a massive explosion. 
  
 Some estimates put it at 100 kilotons, which would be five times more powerful than Fat Man, the bomb dropped on Nagasaki by the US in 1945 and which killed 70,000 people instantly. 
  
 But it still pales in comparison to the largest man-made explosion ever on Earth - the Soviet Union's Tsar Bomba - King of Bombs - detonated in 1961 in the height of the nuclear arms race. 
  
 That hydrogen bomb unleashed a staggering power of 50,000 kilotons, or 50 megatons. 
  
 Reports at the time said the Tsar Bomba destroyed all buildings within 55km (35 miles) of the test site at Sukhoy Nos in the Arctic Novaya Zemlya archipelago. 
  
 Buildings were destroyed and windows broken for hundreds of kilometres all around. There were reports of broken windows in Finland and Norway, and the shockwave generated by the blast travelled around the planet three times. 
  
 It was a physically an enormous bomb, weighing 27 tonnes and about 8m in length, meaning it was entirely impractical as a genuine weapon. It was dropped by parachute, from a manned plane. The crew survived, though that had been far from a certainty. 
  
 It later emerged that the bomb could have been even more powerful - it was originally designed to generate a 100-megaton blast, but was scaled back to prevent the nuclear fallout affecting the wider population. 
  
 The Soviet Union carried out several other tests of immensely powerful nuclear weapons in the 1960s in Novaya Zemlya, which had a yield of 20-24 megatons. 
  
 But more than half of the more than 2,000 deliberate nuclear explosions since the dawn of the nuclear weapons age in July 1945 have been by the US, still the only country to use nuclear weapons in war. 
  
 In November 1952, the US blew up the world's first hydrogen bomb - a far more powerful nuclear device than atomic bombs. Codenamed Ivy Mike, the 82 tonne-weapon was detonated in the Marshall Islands in the Pacific Ocean. 
  
 It had an explosive power of 10 megatons. 
  
 Image copyright AFP Image caption The US hydrogen bomb explosion in 1952 
  
 Archive news footage of the blast shows observers watching from military boats about 50km away. 
  
 Harold Agnew, a physicist and leading figure in US nuclear programme, was on board one of the boats, and later said: "Something I will never forget was the heat. Not the blast... the heat just kept coming, just kept coming on and on. It's really quite a terrifying experience." 
  
 The blast cloud was about 50km high and 100km wide, and completely destroyed the island of Elugelab. 
  
 Image copyright AFP Image caption A huge concrete dome covers the site on Runit Island in the Marshall Islands where repeated nuclear tests were carried out 
  
 But the biggest ever nuclear device detonated by the US was Castle Bravo, in 1954 at Bikini Atoll in the Marshall Islands. 
  
 Castle Bravo is mostly remembered for its unintended after effects. It was expected to have a yield of about 5,000 kilotons, but the scientists had miscalculated and the eventual yield was three times that. 
  
 The resulting mushroom cloud was more than four miles wide and radiation spread over 11,000 sq km. 
  
 Image copyright Science Photo Library Image caption This 1956 test was one of several carried out in Bikini Atoll in the 1950s 
  
 People nearby had been evacuated - many never to return - but the effects were wider than expected. In the days afterwards, hundreds more people across neighbouring atolls were exposed to nuclear fallout, as well as the crew of a Japanese fishing boat in the area, leading to radiation sickness. 
  
 In 1997, the International Atomic Energy Agency said the Bikini Atoll should "should not be permanently resettled under the present radiological conditions". ||||| Tweet with a location 
  
 You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more ||||| WASHINGTON — President Trump is considering pulling out of a major trade agreement with South Korea as he tries to fulfill get-tough campaign pledges on international trade. But he has not yet made a final decision, two senior administration officials said Saturday. 
  
 The president’s top economic advisers remain deeply divided over a possible withdrawal from the United States-Korea Free Trade Agreement, as negotiators from both countries struggle to rewrite the five-year-old deal. 
  
 The debate comes as the United States and South Korea are working together to try to combat a growing nuclear threat from North Korea, which said on Sunday that it had tested a hydrogen bomb that could be mounted on an intercontinental ballistic missile. It is a more powerful weapon than the atomic bomb it had tested in the past. 
  
 In recent days, a frustrated Mr. Trump has pushed his staff to take bold action against a host of governments, including the one in Seoul, that he has accused of unfair trade practices. But many of his more moderate advisers, including the chairman of the National Economic Council, Gary D. Cohn, believe that such a move could prompt a trade war that could hurt the United States economy. ||||| Texas Sen. Ted Cruz said President Donald Trump "speaks in ways that I wouldn't" on North Korea but that it helps to "have a president who is strong." 
  
 Interested in North Korea? Add North Korea as an interest to stay up to date on the latest North Korea news, video, and analysis from ABC News. Add Interest 
  
 The Republican senator told ABC News "This Week" co-anchor Martha Raddatz that if North Korea's claim that it successfully tested a hydrogen bomb Sunday is true, it is "a serious escalation in their ability to commit mass acts of murder" that will spur calls for "further serious steps to prevent North Korea from using those weapons." 
  
 "North Korea right now, it’s the most dangerous place on the face of the planet," Cruz said on "This Week" Sunday. "Kim Jong Un, who’s the dictator there, he is radical, he is unpredictable, he is extreme, and he’s getting more and more dangerous weapons." 
  
 Raddatz asked Cruz about Trump's prior warning that the United States would respond with "fire and fury" to any further provocations from North Korea. 
  
 "Do you think [the president's threat] hurt or helped?" she asked. 
  
 "The president speaks in ways that I wouldn't speak, but that is his prerogative," the Texas senator said. "I do think it helps for North Korea and for China to understand that we have a president who is strong." 
  
 "I think the president is right that Kim Jong Un and other bullies only understand and respect strength, that weakness, that appeasement, encourages this action," Cruz said. 
  
 He added, "In term of what happens, listen, no rational person wants to see a military conflict with North Korea, with the nuclear weapons ... [In] almost any scenario, you're looking at tens of thousands or hundreds of thousands of casualties in a matter of days.' 
  
 President Trump tweeted about North Korea’s nuclear test this morning, saying Pyongyang's, “words and actions continue to be very hostile and dangerous to the United States.” 
  
 He continued, “South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!” 
  
 South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing! — Donald J. Trump (@realDonaldTrump) September 3, 2017 
  
 North Korea has conducted a major Nuclear Test. Their words and actions continue to be very hostile and dangerous to the United States..... — Donald J. Trump (@realDonaldTrump) September 3, 2017 
  
 ..North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success. — Donald J. Trump (@realDonaldTrump) September 3, 2017 
  
 Asked what the president meant by his tweet, Cruz said, “I think the president is right that Kim Jong Un and other bullies only understand and respect strength, that weakness, that appeasement, encourages this action.” 
  
 “In term of what happens, listen, no rational person wants to see a military conflict with North Korea, with the nuclear weapons, there almost any scenario, you're looking at tens or thousands or hundreds of thousands of casualties in a matter of days,” he said. 
  
 The Texas senator also reflected on the aftermath of Hurricane Harvey, telling Raddatz, “The damage is unlike anything I have ever seen.” 
  
 “This last week has been horrific. Houston is my home,” Cruz said. “In Houston, you're used to hurricanes, that's part of living on the Gulf Coast is you get hit by hurricanes and you come through it. This disaster, Harvey, is unlike anything we have ever seen.” 
  
 Cruz praised the public's response, “In the face of that disaster, we've seen incredible bravery.” ||||| North Korea announced on Sunday that it had conducted a nuclear test using an advanced hydrogen bomb, also known as a thermonuclear bomb, marking departure from its experiments with first generation atomic weapons. But what's the difference between an atomic bomb and the more advanced hydrogen bomb? 
  
 Read more: North Korea: From war to nuclear weapons 
  
 Detonation 
  
 The fundamental difference between a hydrogen bomb and atomic bomb is in the detonation process. For an atomic bomb, such as the ones dropped on Nagasaki and Hiroshima, its explosive power is a result of the sudden release of energy upon splitting the nuclei of a heavy element, such as plutonium. This process is known as fission. 
  
 Years after the first atomic bomb was developed in New Mexico, the US developed a weapon that relied on the technology of the atomic bomb, but expanded the detonation process to create a stronger explosion. That weapon is called a thermonuclear bomb. 
  
 For a thermonuclear bomb, the detonation process comprises several parts, beginning with the detonation of an atomic bomb. The first explosion creates temperatures of millions of degrees, providing enough energy to force the two light nuclei close enough to combine in a second stage known as fusion. 
  
 Shape 
  
 According to experts, North Korea's latest bomb showed a marked difference from previous ones, displaying a chambered device that suggests a two-stage hydrogen bomb. 
  
 "The pictures show a more complete form of a possible hydrogen bomb, with a primary fission bomb and a secondary fusion stage connected together in an hourglass shape," said Lee Choon-geun, senior research fellow at the state-run Science and Technology Policy Institute in South Korea. 
  
 Power 
  
 The yield of a thermonuclear bomb can be hundreds to thousands of times more powerful than the atomic bomb. 
  
 Read more: North Korea crisis: 10 questions, 10 answers 
  
 The explosive power of an atomic bomb is often measured in kilotons, or one thousand tons of TNT, while thermonuclear bombs are generally measured in megatons, or one million tons of TNT. ||||| WASHINGTON — While the world agonized over the huge nuclear test in North Korea this weekend, President Trump aimed his most pointed rhetorical fire not at the renegade regime in Pyongyang, but at America’s closest partner in confronting the crisis: South Korea. 
  
 In taking to Twitter to accuse Seoul of “appeasement,” Mr. Trump was venting his frustration at a new liberal South Korean government he sees as both soft on North Korea’s atomic program and resistant to his demand for an overhaul of trade practices that he views as cheating American workers and companies. 
  
 For Mr. Trump, the crisis lays bare how his trade agenda — the bedrock of his economic populist campaign in 2016 — is increasingly at odds with the security agenda he has pursued as president. It is largely a problem of Mr. Trump’s own making. Unlike several of his predecessors, who were able to press countries on trade issues while cooperating with them on security, Mr. Trump has explicitly linked the two, painting himself into a corner. 
  
 The president, known for fighting his political wars simultaneously on multiple fronts, seems intent on taking on all comers in Asia. The president on Sunday took a somewhat milder jab at another country he sees as an adversary on trade, China, saying the North was an “embarrassment” to Beijing, its primary economic patron. ||||| Tweet with a location 
  
 You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more |||||
Output:
North Korea on Sunday carried out its most powerful nuclear test yet, an underground explosion that caused tremors that could be felt in China and South Korea. Pyongyang is claiming it tested a hydrogen bomb that can be mounted on an intercontinental ballistic missile capable of reaching the American mainland, and experts say the bomb has destructive capacity far beyond the one that destroyed Hiroshima. President Trump around noon on Sunday tweeted, "I will be meeting General Kelly, General Mattis and other military leaders at the White House to discuss North Korea." He added that "the United States is considering, in addition to other options, stopping all trade with any country doing business with North Korea." More on the situation: NBC News also has video of Trump remarking, "We'll see," after a reporter asks if he will attack North Korea. The Washington Post has published a history of nuclear tests and points out that North Korea is the only country to have performed one (or six) in the 21st century. It also explains the estimated yield (meaning how much energy is released in an explosion) was 100 kilotons, versus the yields of the atomic bombs dropped on Hiroshima and Nagasaki, which were 15 and 21 kilotons, respectively. Per the BBC, the "largest man-made explosion ever on Earth" was the Soviet Union's Tsar Bomba in 1961, at "the height of the nuclear arms race." Deutsche Welle explains the differences between the hydrogen bomb Pyongyang claims it tested and the weaker atomic bomb: It really comes down to the "detonation process." Trump responded to news of the test by criticizing South Korea on Twitter, writing "their talk of appeasement with North Korea will not work, they only understand one thing!" The New York Times calls it a "notably harsh line" ... amid an escalating dispute over trade that threatens to weaken a central partnership in the region." More on Trump's debate over whether to withdraw from a major trade deal with the South here. The Hill notes the perspective of a State Department official under Bush: "This is no time to lecture South Korea or suspend free trade agreement. Best way to deter North Korea is to stand firmly with Seoul+Tokyo." Texas Sen. Ted Cruz appeared on ABC News' The Week Sunday morning and was asked what he thought of Trump's handling of the situation. "The president speaks in ways that I wouldn't speak, but that is his prerogative. I do think it helps for North Korea and for China to understand that we have a president who is strong. I think the president is right that Kim Jong Un and other bullies only understand and respect strength, that weakness, that appeasement, encourages this action."