“After World War II, defending America in the modern world required new intelligence agencies, the unification of the armed services under a massive new Defense Department, and later the creation of new civilian organizations with some defense functions, such as NASA and the Energy Department.”

American attorney and national security adviser

Robert Charles O'Brien Jr. is an American attorney and policy adviser, best known for serving as the 27th United States national security adviser from 2019 to 2021. He was the fourth and final person to hold that post in Donald Trump’s first presidency. O'Brien later became chairman of the consulting firm American Global Strategies. His public profile is rooted in national security and foreign policy work, especially in senior government service and strategic advisory roles.