In late October 2018, sixteen packages containing pipe bombs were mailed via the U. S. Postal Service to several prominent critics of U. S. President Donald Trump, including leading Democratic Party politicians such as former U. S. President Barack Obama, former U. S. Vice President Joe Biden, and former U. S. Secretary of State Hillary Clinton. While the packages were initially treated as live bombs, analysis indicated some of them could not explode, though it is unclear if they were "intentional" duds.