Former Amazon worker Kao Xiong admits sending bizarre bomb threats to Donald Trump and US ex-presidents, warning of ‘Unstoppable Force’ group
- Kao Xiong – who suffered a ‘touch of mental illness’, according to his lawyer – also sent threats to a Hmong TV station, the Mall of America and Yahoo
- Xiong included in some of his threats the contact details of an FBI agent who was investigating him

Kao Xiong apparently had a thing for letter writing, mailing out more than 150 letters since January 2017 to US President Donald Trump, former presidents, an FBI agent, Dallas/Fort Worth International Airport and a number of individuals.
The letters from Xiong, a 34-year-old from Oroville, California, contained a number of death threats, bomb threats and extortion demands, as well as references to a group he called the ‘Unstoppable Force’,” federal court records say.
“Pipe Bomb, Everyone is going to die,” one letter sent to DFW airport offices in Texas read, according to court records.
That letter and dozens of others, some containing white powder later determined to be flour, prompted “expenditure of significant taxpayer dollars” and hazardous materials response by officials trained in handling weapons of mass destruction, according to a criminal complaint filed under seal against Xiong in December 2017.
‘US mail bomber’ with van covered in Trump stickers is arrested in Florida
On Thursday, Xiong appeared in a federal courtroom in Sacramento and pleaded guilty to a single count of using the mail to convey a malicious threat about an explosive device, an offence that carries a maximum prison term of 10 years.