Lyndon B. Johnson assumed the presidency in the wake of the assassination of John F. Kennedy in November 1963. He gave a speech to Congress solemnly embracing his duties five days after the assassination, pledging to advance the domestic programs and initiatives of his predecessor and, in foreign affairs, to balance U.S. military strength with restraint. He met with success on the former front but is considered to have failed on the latter. In trying to deal with the worsening military situation in Southeast Asia, he made the fateful decision, in mid-1964, to expand American involvement in South Vietnam—despite the uncertain military intelligence concerning North Vietnamese aggression in the Gulf of Tonkin.