The Kennedy Center in its "Hall of Nations" does not display the Iranian, Cuban or North Korean flags -- nor the Palestinian ofcourse. I remember it not displaying the Iraqi flag in the 90s. They have a handout saying that the flags are of the "countries with which the US maintains diplomatic relations."
It always seemed rediculous to me that a cultural building would be named for a political leader.
(Addition: This doubly doesn't make sense. The "Hall of Nations" only includes "nations" (including the Vatican) with which the US government has diplomatic releations. So it doesn't include actual nations with non-trivial populations like Iran, Cuba and North Korea. Meanwhile, at the other end of the building, the "Hall of States" includes the flags of such things as Washington, D.C. and Guam -- which are clearly not states.)