A "state" is not a "nation", so claiming that Indian reservations are "sovereign nations" does not make those reservations into "states". Fer' cryin' out loud, they are managed under the auspices of the United States Department of the Interior! And they certainly fail the first test of statehood i.e. they can not enter into international agreements with other states.
from the article: Clinton: Two-state solution still possible for Israel, Palestinians