The goal of declass R package is to allow people explore the vast archival records from Columbia University History Lab - Declassification Engine.

Columbia History Lab Archives
Columbia History Lab Archives

Example

library(declass)
# See what collections are there
declass_collection()
# See what entities are there the in the kissinger collection
declass_collection_entity("kissinger")
# See what countries were mentioned and how many times there're mentioned in the kissinger collection
declass_entity_data("kissinger", "countries")