In December 2021, a former FBI agent previously posted to Guangzhou in China began legal proceedings against the US government. The agent claimed the US Secretary of State and the Department of State hadn’t taken the situation seriously enough when, while in Guangzhou, the agent and his family had begun experiencing sudden headaches, dizziness, nosebleeds, memory loss and nausea.
It was the latest development in a saga that began to unfold in 2016 when dozens of staff at the US embassy in Cuba started describing similar symptoms, often accompanied by an ear-splitting sound and facial pain.