I think that Johnson gave into public pressure from the foreign advisors to send troops to Vietnam.
But Lyndon Johnson never gave into pressue from his team of foreign advisers regarding the War in Vietnam. He was a staunch believer in the Domino Theory likewise with President's Eisenhower and Kennedy before him and President Johnson would do anything to stop South East Asia from falling under Communist influence. Why do you think then within weeks of succeeding President Kennedy in the White House that Johnson granted the South Vietnamese Government an extra $500 million in military aide to fight off the North Vietnamese? Lyndon Johnson never gave into pressure my friend, he was still afraid of Cold War hysteria that is all.