"U.S. is Said to Seize 374 P.O.W. Letters."
New York Times, September 17, 1970, p. 4.
A group formed by the international section of the Black Panther Party called the "United
States Peoples' Anti-Imperialistic Delegation," was returning to the United States from an
international trip when 374 letters from P.O.W.'s was seized by United States Customs officials.
(An explanation for the seizure was given the
next day and can be found here).