“It is not clear North Korea has that capability yet,’’ said Siegfried S. Hecker, the former director of Los Alamos National Laboratory and the nuclear weapons expert the North Koreans let in to see their uranium enrichment plants years ago, when they wanted to make clear to the Obama administration that their atomic weapons program was moving ahead, unimpeded by sanctions.
“Besides,” said Dr. Hecker, now a professor at Stanford University, “a live missile test — one loaded with an H-bomb — poses enormous risk.” He recalled that when the United States performed such tests in the early days of the Cold War, “one blew up on the launchpad and one had to be destroyed right after launch, creating significant radioactive contamination.”
The North Koreans have studied this history, too, according to current and former American intelligence officials. But the appeal of an atmospheric test is obvious: It would create a sense of fear that an explosion deep inside a tunnel in North Korea does not. The underground tests are detected on a Richter scale; an atmospheric test, like the kind the United States conducted at Bikini Atoll starting in 1948, creates a terrifying mushroom cloud.
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The largest of those, a 1954 test code-named Castle Bravo, turned out to be roughly three times larger than American bomb designers anticipated. They had made a mathematical miscalculation about the power of one of the nuclear fuels contained in the weapon, and the explosion spread radioactive material across the globe. Ultimately, Castle Bravo helped fuel the call for a ban on atmospheric tests.
No one knows what kind of test the North Koreans have in mind; the country’s foreign minister, Ri Yong Ho, did not specify when he raised the possibility when talking to reporters at the United Nations on Thursday. “This could probably mean the strongest hydrogen bomb test over the Pacific Ocean,” he said. “Regarding which measures to take, I don’t really know since it is what Kim Jong-un does.”
But the presumption is that if Mr. Kim decided to go ahead, the North would attempt to conduct the test by firing it on a missile, presumably to an empty spot in the Pacific. The goal would be to demonstrate that it had solved all the technological issues involved in delivering a nuclear weapon to an American city.
But that form of testing — putting a live weapon on a missile — is particularly risky. Other countries have blanched at the potential for disaster, Dr. Hecker noted, including the Chinese, who conducted one missile launch with a live nuclear weapon in the warhead. It worked as planned, he said, but “the Chinese considered the risks unacceptable” and never tried it again. In the hands of the North Koreans, some say, it would be even riskier.
“This would be a regional nightmare” for East Asia, said Heather Conley, a former senior State Department official, now at the Center for Strategic and International Studies in Washington.
It is possible the threat will never come to fruition. Detonating a weapon inside a missile warhead, or even from a ship or barge, would be far more difficult for the North than setting one off inside a mountain, where engineers have months to wire up the weapon, and no time pressure.
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It would require what experts call a “weaponized device” that could survive shocks, stresses and, if launched from a missile, the heat of re-entry into the atmosphere, something North Korea has never demonstrated it can handle.
“The DPRK would be taking a big risk — missile tests fail,” said Philip E. Coyle III, a nuclear scientist and former head of the Pentagon’s weapons testing. The live nuclear warhead could come down on a neighboring country, or if the missile blew up on the launchpad — as has been known to happen — set off the nuclear warhead in North Korea.
The transportation risks would be enormous, including the chance of an accidental detonation before the nuclear device reached the target zone. And while the world’s best missiles fail roughly once in every 100 flights, the failure rate for the North’s missiles is much higher. Last year, one type of missile failed seven out of eight times, perhaps in part because it had been targeted by a series of cyber attacks ordered by President Barack Obama. Since then, the North has ceased testing that type of missile and been more successful with others.
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And even if one of the North’s missiles succeeded in lofting a nuclear weapon, the bigger challenge would be bringing it back down during the fiery re-entry. The heat, pressures and forces of deceleration are enormous. To date, evidence from the North’s test launches suggests it is still in the beginning stages of learning how to build a survivable warhead.
It would be far easier for the North to entrust a nuclear weapon to a plane or a boat. But it has few with the long-range capability for the job, and the chances that the United States or its allies would detect it in transit are considerable.
It would also break a taboo. It has been 37 years since any nation tested a nuclear weapon in the planet’s atmosphere. And given what is now known about the effects that radioactive fallout from such tests has on human health and the environment, one now would only intensify the international opprobrium Mr. Kim already faces.
According to one estimate by a physicians group opposed to nuclear weapons, 2.4 million people could die from cancer caused by the radioactivity from the more than 2,000 known tests that have already taken place.
The last atmospheric test took place on Oct. 16, 1980, when China fired what experts believed to be a nuclear-tipped ballistic missiles into a desert salt flat along what was once the Silk Road, more than 1,300 miles west of Beijing.
The United States attempted a missile-launched nuclear test so only once — on May 6, 1962 — during a frenzy of Cold War tests. A submerged submarine, the Ethan Allen, fired a Polaris A-2 missile in the direction of Christmas Island in the Indian Ocean. After traveling more than 1,200 miles, its warhead exploded at an altitude exceeding 10,000 feet.
A video of the United States’s first and only test of an operation nuclear weapon “mated” to a ballistic missile, conducted in the Pacific Ocean on May 6, 1962.Video by rai85archive
That test helped spur negotiations that ultimately led to a treaty banning tests in the atmosphere, outer space or underwater. It was in signed in 1963 by the United States, the Soviet Union and Britain.
In 1996, a far broader agreement to ban all nuclear testing, the Comprehensive Test Ban Treaty, was adopted at the United Nations and has been ratified by 166 states. The United States, China and North Korea are among the holdouts, along with Egypt, India, Israel, Iran and Pakistan.
An effort by the Clinton administration to ratify the treaty failed; Mr. Obama promised to resubmit it for ratification but never did, fearing a second defeat. The United States and China have adhered to its restrictions, even if neither has ratified it.
President Trump applauds during a rally for Sen. Luther Strange at the Von Braun Center in Huntsville, Ala., on Friday. (Brendan Smialowski/AFP/Getty Images)
HUNTSVILLE, Ala. — President Trump campaigned on Friday night for Alabama Senate candidate Luther Strange, in a race that has pitted him against his most loyal supporters and that holds the potential to upend the political dynamics for Republicans facing election in 2018.
The endorsement of ‘Big Luther’ could prove to be a big boost for the interim Alabama senator, who is trailing his opponent, former state judge Roy Moore, in some public polls. But even Trump seemed unsure that the endorsement was the right move.
“I’ll be honest, I might have made a mistake,” Trump told the crowd at one point during his more than 30 minutes of remarks.
“If Luther doesn’t win they’re not going to say, we picked up 25 points in a short period of time,” he added, referring to the media. “If his opponent wins, I’m going to be here campaigning like hell for him.”
After some musing, he seemed to catch himself.
“Luther will definitely win,” Trump said.
It may not have been exactly the ringing endorsement Strange’s campaign had hoped for, but it would have to do.
Trump is jumping into the special election at a time when Strange could use all the help he can get before the primary election on Tuesday night. The Alabama Republican is favored by establishment Republicans including Senate Majority Leader Mitch McConnell (R-Ky.), but has been pilloried by Moore, who has fashioned himself as an outsider Republican in the mold of Trump himself.
For his part, Strange has draped himself in Trump in an effort to win over the president’s ardent supporters. So much so that the Friday night rally bore few signs that its purpose was to boost his candidacy.
Everything about the rally — the mega stadium, the massive American flag, the “Make America Great Again” hats — screamed Trump. There were few signs that the rally was for anyone else, except for the giant Trump campaign-styled “Vote for Luther” sign that hung in the background.
The president delivered a signature rally speech, meandering from topic to topic, prompting laughter, and chants of “Lock her up!” from the crowd when he mentioned his former Democratic opponent, Hillary Clinton. He denounced the “dishonest media” who he said would not broadcast images of the crowd (though they often do). And he complained about the treatment of first lady Melania Trump in the media.
Then, without much warning, Trump returned to his prepared remarks touting Strange.
“Luther wants to end business as usual, stop the insider dealing and Luther Strange is determined to drain that swamp,” Trump said, in a brief interlude.
Trump talked at length about Strange’s willingness to vote in favor of the Republicans’ bill to repeal the Affordable Care Act without seeking any favors in return. He said his endorsement of Strange came despite his unwillingness to wade into an ongoing primary.
“We have to be loyal in life,” Trump said. “He never went quid pro quo, he just treated me great.
“And I’m calling him. He was down like quite a bit and I said I’m going to endorse you,” Trump continued. “I shouldn’t be doing it … The last thing I want to do is be involved in a primary.”
But Strange had given him one of the “coolest” moments of the last six months of his life, Trump told the crowd. So he came to Alabama to get out the vote for Strange in the final days of the primary campaign.
But, quickly, Trump was back to his usual campaign fare.
He boasted of his electoral college win.
“They said there was no path to 270 but there was a path to 306,” Trump said.
He admonished Clinton for failing to travel to Wisconsin during the campaign and dismissed the idea that Russia interfered in the election to help him.
“In case you were curious, no, Russia did not help me,” Trump declared.
He returned again to Strange, who apparently watched the rally from somewhere offstage.
Both men were on message on one important point: The Senate majority leader was persona non grata.
“He’s not a friend of Mitch McConnell, he doesn’t know Mitch McConnell until recently,” Trump said, decrying the “bad rap” that Strange’s opponents had saddled him with as an establishment candidate. “He doesn’t know him, he just got there!”
Moore, a controversial former state judge, boasts the support of prominent pro-Trump figures, including two ex-White House staffers, chief strategist Stephen K. Bannon and his terrorism aide, Sebastian Gorka.
At a rally in Montgomery on Thursday night, former Republican vice presidential nominee Sarah Palin pitched the race, and Moore’s candidacy, as a fight for the soul of Trumpism.
“A vote for Judge Moore isn’t a vote against the president,” Palin said. “It is a vote for the people’s agenda that elected the president. It’s for the big, beautiful movement that we’re all a part of. The president needs support to keep the promises that elected him. So we’re sending Trump someone who has our back, not Mitch McConnell’s … Make no mistake, ‘Big Luther’ is Mitch McConnell’s guy.”
The dissent among Trump allies even came from within his own Cabinet.
Housing and Urban development Secretary Ben Carson issued a statement on Friday backing Moore’s candidacy, an extraordinary endorsement that came just hours before Trump was set to arrive in Alabama to campaign for Strange.
“Judge Moore is a fine man of proven character and integrity, who I have come to respect over the years,” Carson said. “He is truly someone who reflects the Judeo-Christian values that were so important to the establishment of our country.”
Recent polling in the state shows Strange trailing Moore despite the political muscle backing him.
Republicans worry that if Strange falls to Moore, the race could launch a tsunami of outsider challenges to incumbent Republican lawmakers in the next midterm election.
Trump warned the crowd that Moore would be vulnerable to losing to the Democratic candidate in the general election while Strange would sail through to victory.
“Roy has a very good chance of not winning in the general election,” Trump said. “Roy is going to have a hard time, but I will be backing him if he wins.”
And he lamented that Strange, who he noted had fought against public corruption in his previous career as attorney general of Alabama, had been saddled as an establishment candidate. Strange was appointed by the Alabama governor to fill the seat vacated by former senator Jeff Sessions, who has become the U.S. attorney general in the Trump administration.
“Friends of mine have told me very strongly that if Luther wasn’t appointed in office … he’d be leading every poll by 50 points,” Trump said. “But the fact that he got appointed hurt him.
“If Luther didn’t take an appointment, if he just ran, it wouldn’t be a contest,” Trump said.
As Trump faces the prospect that his chosen candidate might not emerge the victor, he has fixated on what his endorsement has done to help Strange catch up in the polls.
“If Luther doesn’t make it, they’re going to go after me,” Trump said, referring to the media. “He went to third, second and now it’s almost pretty even right?”
