There is a dangerous confluence between anti-Zionism and anti-Semitism, though the two concepts are not always identical. Anti-Zionism is often used to conceal hatred of Jews. Anti-Semitic views can be easily distinguished from legitimate criticism of Israel.
When approached by a student who attacked Zionism, Dr. Martin Luther King responded: When people criticize Zionists, they mean Jews. You're talking anti-Semitism.
(From Seymour Martin Lipset, The Socialism of FoolsThe Left, the Jews and Israel, Encounter, (December 1969), p. 24.)
Source: Adapted from Shamash