A counter terrorism specialist has blamed US president Donald Trump for a spate of glass-filled pipe bombs sent to Hillary Clinton, former president Barack Obama and other prominent Democrats, as well as the CNN offices.
Simon Trundle said responsibility for the crude bombs had to "land back at Donald Trump's doorstep" for openly criticising Clinton and Obama, and calling them "enemies of the state".
"How did they get motivated to do this? I'm afraid that has to land back at Donald Trump's doorstep, because for two years now he's been going round calling these people enemies of the state, getting his people to shout lock her up, attacking Barack Obama," Mr Trundle told talkRADIO's Julia Hartley-Brewer.
'Easy to inspire a mad man or woman'
Federal and city investigators arrive at the scene of a reported suspicious package at a US Postal Service mail facility. Image: KABC-TV
"It's easy to inspire a mad man or woman, or a group, point a target out to them and claim no responsibility when they act upon it.
"When you stoke a narrative of separation and they're the enemy and we're the heroes, once you start stoking that there's always going to be a nutter or two out there that suddenly thinks he or she has been given justification by their leaders."
The targets of the bombs were some of the figures most frequently criticised by president Donald Trump.
"For Trump to have referred to them [Hillary Clinton] as the most hated person in America, and for Fox News to giver her that title several times, there has to be some degree of responsibility," Mr Trundle said.
He added: "The hypocrisy this morning of watching Trump saying we've got to stop this endless hostility and how we speak negatively about others. I think he needs to look in the mirror."
The first crude bomb to be discovered had been delivered on Monday to the New York compound of George Soros, a liberal billionaire and major contributor to Democratic causes.
A bomb was also sent to the New York offices of CNN, which resulted in the broadcaster evacuating the building live on air.
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A law enforcement official said the bombs were packed with powder and shards of glass, and were made from PVC pipe about six inches long, and covered with black tape. None of them detonated.
Mr Trundle criticised the sender of the bombs, saying the move "wasn't really very clever".
"The stamps are not put on with a simple moist sponge, they're individually licked and put in place. There's lots of forensics on this package," he said.
"The FBI resources in tracking and tracing people are incredible. They will take this as a personal affront, so will of course the secret service who are tasked to protect both of the key target individuals."