Image : Tom McKay ( Gizmodo )

The Chinese government has almost certainly not secretly detonated a tactical nuclear weapon in the South China Sea to send a warning signal to the United States, experts told Gizmodo, regardless of widespread claims to the contrary on social media.




The source of this particular rumor appears to be Hal Turner, a far-right New Jersey radio host and former FBI informant considered a white supremacist b y the Anti-Defamation League and the Southern Poverty Law Center (and who once was sentenced to nearly three years in prison for calling for the murder of three federal judges). A post on Turner’s website claimed that unidentified “military sources” had said that around 6:22 p.m. ET on Wednesday, a nuclear explosion of some kind 50 meters below the surface of the South China sea had “caused an underwater shock wave of such sudden presence, and of such strength, that the explosion itself ‘had to be between 10 and 20 Kilotons.’” Later, the article on Turner’s website was updated to claim that the uRADMonitor Global Environmental Monitoring Network had detected “significant” radiation readings on the southern coast of China near Zhangjiang and Hong Kong, as well as Taiwan.

Turner speculated that the Chinese government had detonated a nuclear weapon to quietly send a signal to the U.S. government that it was fed up with intervention against Chinese oppression of pro-democracy protests in Hong Kong, the ongoing U.S.-China trade war, or perhaps simply to suggest that World War III was around the corner:

Did China detonate a small, tactical, nuclear device to send a warning to the United States over the US Senate and US House approving the Hong Kong Democracy Act, which China views as an “assault” upon China’s internal affairs? Has China had enough of US “freedom of navigation” exercises in the South China Sea? Is China feeling the sting of economic downturn from its Trade War with the USA, and are they “upping-the-ante” signaling actual war?


This is normally the kind of thing that reasonable people would simply ignore. But thanks in part to a series of tweets from an account using the official-sounding handle “IndoPacific_SCS_Info” and others, Turner’s claims gathered the attention of thousands on Twitter.



This one is particularly good:


It should come as no surprise that this is hot bullshit. For one, the uRADMonitor site itself pegs the supposedly gigantic radiation spike at 0.24 microsieverts per hour. That’s about the same as in South India, parts of the southwestern U.S., and Mexico—and it is an absolutely negligible amount of radiation. For comparison, the World Nuclear Association estimates the global average of naturally occurring background radiation at 0.17-0.39 microsieverts per hour, according to Reuters. If one were exposed to 0.24 microsieverts per hour, that would equate to around 2,100 microsieverts a year, or just over two millisieverts. The U.S. defines the upper boundary of safe occupational exposure at 50 millisieverts per year.

One university radiation safety specialist, who spoke anonymously with Gizmodo because they were not authorized to talk to the media, confirmed that the supposedly ominous uRADMonitor readings appeared to reflect normal background radiation levels and called the claims “unsupported wild-ass speculation.” (That specialist also warned that uRADMonitor was not a reliable source.) Readings of airborne radioactive particles posted on the Environmental Protection Agency’s RadNet Honolulu page, as well as the Institute for Information Design Japan’s Japan Radiation Map, also seemed to show nothing out of the ordinary (other than elevated levels in the area of the 2011 Fukushima Daiichi nuclear disaster).


That’s generously assuming that those readings even matter in the context of a covert underwater Chinese nuclear explosion, which Gizmodo has it on good authority they don’t.

Gizmodo spoke with Robert Rosner, a former Department of Energy scientist and current University of Chicago theoretical physicist who chairs the Bulletin of the Atomic Scientists’ Science and Security Board. Rosner laughed at the idea that anyone would be able to identify an underwater nuclear test from ground-based detectors, or that anyone would be stupid enough to conduct such a test in the South China Sea.


“I would be amazed if there had been an event that somebody would then identify as an event based on a radioactive signature,” Rosner told Gizmodo via phone. “That’s unbelievably unlikely.”

Rosner added that the primary way of detecting such an event would be seismic; the first underwater nuclear tests in the world, the 23-kiloton Baker nuke at Bikini Atoll in 1945, set off seismographs the world over. There’s been no such indication that any kind of similar event happened on Wednesday.


“We detect underground events,” Rosner said. “The standard way is a network of sensing stations around the world. They sense both underground explosions as well as underwater explosions, and even if you have an above-water event, it would create a seismic signal in the sea.”

“If you go to do a surreptitious test, which is what this presumably would be, the South China Sea is one of the last places someone will go do that,” Rosner added. “... It’s a very populated place. ... There’s a lot of people hanging around there. It’s an area that’s under heavy surveillance because of what the Chinese are doing there, so the odds of somebody trying to do something nefariously there is just so unlikely.”




Rosner continued: “There is so much surveillance that it would be stunning if no one had noticed that. And it would not have been noticed on the basis of radioactive debris, especially because underwater there wouldn’t be any debris ... above the ocean surface.”



In addition to security concerns, Rosner said, the region is also monitored for seismic events because of “really deadly tsunamis” like the 2004 Indian Ocean earthquake and tsunami. Rosner said that a 10-20 kiloton blast would “definitely be notable” on that scale, noting that the nuclear bombs dropped on Hiroshima and Nagasaki were of similar magnitude.


In other words: You should not believe a racist radio host who says completely unremarkable background radiation readings are evidence that China is about to start World War III.

Rosner suggested a list of tips for anyone trying to quietly carry out a nuclear test. Don’t do it underwater, and instead send the bomb out on a flotation device somewhere remote, like the suspected South African/Israeli nuclear test near the Prince Edward Islands in the sub-antarctic Indian Ocean in 1979.


“You’d wait for a very cloudy day” to make it harder for satellites to spot it, Rosner said. “That could potentially be difficult to detect. But doing it underwater, it’s just, yeah, that’s not a smart thing.”