Answer:
Lyndon B. Johnson
Explanation:
Lyndon Baines Johnson, widely known by his initials LBJ, was the 36th President of the United States of America who took the presidency following the assassination of the previous President John F. Kennedy from 1963 to 1969.
He spent most of his term dealing with the Vietnam War and escalated American involvement in it. By 1964, he was granted the power to use military force in Southeast Asia without having any permission for an official declaration of war and so 20,000 U.S. troops were sent to the Vietnam.