US National Security Adviser Mike Waltz accidentally added journalist Jeffrey Goldberg to a private Signal group discussing potential military strikes in Yemen due to a phone contact error. The mistake was caused by an auto-save feature on Waltz's iPhone, leading to a White House investigation. Despite no classified information being leaked, the incident reportedly upset President Trump. However, Waltz was not fired as a result of the error. The mishap highlights the importance of ensuring secure communication channels within government agencies.