1981 - Pakistan and Obama?

Alright all you conspiracy theorist, here’s one for you. Obama traveled to Pakistan at age 20 (he has claimed this a number of times). That would make the year 1981.

Answer the following question – what passport did he travel under?

If it was a British passport, that would provide proof that he was born in Kenya not in Hawaii, otherwise he wouldn’t be eligible to have a British passport. If it was an Indonesia passport, then that would prove he relinquished whatever previous citizenship he held (British or American) prior to being adopted by his Indonesian step-father in 1967, again, otherwise he wouldn’t be eligible to have a Indonesian passport.

Right now everyone is saying ‘Hey dummy, Obama traveled under a U.S. passport, Duh.’. The problem with that is that if he had a U.S. Passport in 1981 he couldn’t have used it to get Pakistan in 1981, Pakistan was on the U.S. State Department’s “No Travel / Banned” list in 1981 and no Americans were permitted to travel there!

So how exactly is it that Obama got to Pakistan in 1981 while also being eligible to be President of the United States?