From October 22 to November 1, 2018, 16 packages found to contain pipe bombs were mailed via the U.S. Postal Service to several Democratic Party politicians and other prominent critics of U.S. President Donald Trump. Targets included former U.S. President Barack Obama, former U.S. Vice President Joe Biden, and former Secretary of State Hillary Clinton.
Other people who were sent packages included three Democratic members of Congress: Representative Maxine Waters, Senators Cory Booker and Kamala Harris; former U.S. Attorney General Eric Holder, two former intelligence chiefs: ex-CIA Director John Brennan and ex-Director of National Intelligence James Clapper; two billionaire Democratic donors and activists: George Soros and Tom Steyer; and actor Robert De Niro. One package was addressed only to CNN and sent to its world headquarters.
The Federal Bureau of Investigation (FBI) and other federal, state, and local law enforcement agencies coordinated their investigations of the attempted bombings. All sixteen confirmed bombs sent were improvised explosive devices, though none had a trigger mechanism. None of the devices exploded outside a controlled setting.
Cesar Altieri Sayoc, Jr. was arrested in Florida on October 26, held without bail, and charged with five federal crimes the following week. The FBI investigated the case as domestic terrorism. On March 21, 2019, Sayoc pleaded guilty to 65 felony counts, including using weapons of mass destruction in an attempted domestic terrorist attack. He was sentenced to a maximum of 20 years in prison on August 5, 2019, and will be eligible for release as early as November 10, 2035.