国家核安全局最近在内华达州进行了一次地下爆炸试验，以更好地理解并可能识别外国核爆炸。
The National Nuclear Security Administrationrecently conducted an underground explosive test in Nevada to better understand and potentially identify foreign nuclear detonations.
为什么重要：国家核安全局局长布兰登·威廉姆斯此前曾向Axios表示，中国“显然”正在进行核爆炸试验，并“试图隐瞒”，这加剧了今年国务院军控官员提出的指控。北京否认了这种情况，并指责美国在挑拨离间。双方都签署了《全面禁止核试验条约》，但尚未批准。
Why it matters: NNSA boss Brandon Williams previously told Axios that China is "clearly" conducting explosive nuclear testing and "trying to hide it," amplifying accusations made this year by State Department arms officials. Beijing has denied such a regime and accused the U.S. of stirring the pot. Both have signed the Comprehensive Nuclear-Test-Ban Treaty.
细节：国家核安全局的试验在位于内华达国家安全站第12区的P隧道内进行，该隧道凿入一座台地的侧面，该站点位于拉斯维加斯西北方向，是一个广阔的保留区。
Neither has ratified it.
试验依赖于化学高爆炸剂和放射性示踪剂。根据该局的说法，试验中收集的数据将用于改进探测模型和算法。
Zoom in: The NNSA test was done inside P Tunnel, cut into the side of a mesa, at Area 12 of the Nevada National Security Site, a massive reserve northwest of Las Vegas. It relied on chemical high explosives and radiotracers.
“探测的可信度仅取决于其背后的数据，”Fuse公司创始人JC·Btaiche对Axios表示。
Data collected from the trial will refine detection models and algorithms, according to the administration.
背景：前国家核安全局副局长弗兰克·罗斯对Axios表示，此类工作对于“提升我们探测低产量核试验的能力至关重要，这是美国核不扩散和国家安全工作的重要组成部分”。
"Detection is only as credible as the data behind it," Fuse founder JC Btaiche told Axios.
他补充说，此类试验“是多年来在多个政府间持续进行的科学、技术和政策工作的成果”。
Context: This type of work is critical "to strengthening our ability to detect low-yield nuclear tests, an essential component of U.S. nuclear nonproliferation and national security efforts," Frank Rose, a former NNSA deputy, told Axios.
回顾：特朗普总统去年秋天曾下令美国恢复核试验，以匹配俄罗斯和中国的水平。
Such trials, he added, "are the product of many years of sustained scientific, technical, and policy work across multiple administrations."
此后鲜有细节披露——且仍有疑问：他究竟是在针对能源部还是国防部？（后者负责进行导弹飞行测试。）全景：美国和俄罗斯的核武库规模远超其他国家；华盛顿和莫斯科共同掌握着全球约90%的核弹头。与此同时，中国正在进行历史性的核武建设。这些武器即便只占一小部分，也足以毁灭地球上的生命。
Flashback: President Trump last fall ordered the U.S. to resume nuclear testing equal to Russia and China. Few details followed — and questions remain about whether he was addressing the Energy Department or the Defense Department. (The latter conducts missile flight tests.) Zoom out: American and Russian nuclear arsenals dwarf all others; Washington and Moscow together wield some 90% of the world's warheads. China, meanwhile, is undertaking a historic buildout. Just a small portion of these weapons could devastate life on Earth.
要点：一名前美国官员向Axios描述NNSA的测试是“在PRC上放一个拇指”。
The bottom line: A former U.S. official described the NNSA test to Axios as "keeping a thumb on PRC."