When Turkey buys Iranian oil, we pay for it in Turkish lira... However, it is not possible for Iran to take that money as dollars into its own country due to international restrictions, the U.S.A.'s sanctions. Therefore, when Iran cannot take this money back as currency, they withdraw Turkish lira a
I would say that the Pentagon Papers case of 1971 - in which the government tried to block the The New York Times and The Washington Post that they obtained from a secret study of how we got involved in the war in Vietnam - that is probably the most important case.

