The American advance team sent to Singapore for the summit between Donald Trump and Kim Jong Un feared that it was being targeted by the same kind of sonic sound attack that have hit U.S. embassies and diplomatic personnel in Cuba and China. A State Department diplomatic security agent who was part of the security team reported hearing an unusual sound he believed was similar to what was experienced by American diplomats who have been diagnosed with brain injuries. The agent immediately underwent medical screening. While Trump was flying in to the summit, the delegation preparing for his arrival was exchanging urgent messages about the potential threat with the State Department headquarters. It turned out to be a false alarm. So far, Americans who have served in at least seven cities in four countries have been tested for possible exposure to the sonic sound attacks, with 26 Americans "medically confirmed" to have been harmed.