Here is one sent via diplomatic pouch from the American Embassy, Phnom Penh.
Arrived Washington, D.C., Sept. 1955
Scott # 14

Miss Garnett spent thirteen months in Cambodia in 1955-1956 working for the International Cooperation Administration as an education consultant. Much of this collection is the result of her work in Cambodia and her continuing interest in that country.
https://scua.library.uni.edu/classi...ca-1955-1979The International Cooperation Administration (ICA) was a United States government agency operating from June 30, 1955 until September 4, 1961, responsible for foreign assistance and 'nonmilitary security' programs. It was the predecessor of the present-day U.S. Agency for International Development.