Initially LBJ did too.
But LBJ came round to Israel's thinking.
And a few years into LBJ's presidency the USA was arming Israel and Israel had nukes.
And Israel attacked the USS Liberty in an attempt to drag the USA into an Israeli war without any consequences.
So on JFK's assassination: cui bono?
JFK wanted Israel tamed.
LBJ unleashed and supported Israeli aggression.
Johnson’s willingness to aid Israel flowed in part from personal concerns. As he told one Israeli diplomat shortly after the assassination, “You have lost a very great friend. But you have found a better one.” Even though he came from a Texas environment populated by few Jews and fewer Zionists, Johnson had worked closely with a variety of pro-Israel figures before coming to the presidency. In many ways, he owed his political career to Abe Fortas, a committed Zionist and the attorney who masterminded his defense in the 1948 election dispute. Fortas remained a counselor to Johnson throughout his career; Johnson named him to a Supreme Court vacancy in 1965.
[source : Robert David Johnson, Lyndon Johnson and Israel: The Secret Presidential Recordings