This search engine, called PlusD, includes cables, intelligence reports, and congressional correspondence, all stored in a database with 61,000 documents classed as 'secret' and 250,000 as 'confidential' in the United States.
WikiLeaks has obtained all these documents and cables from the National Archives and Record Administration (NARA) and gathered them into a single database. To use it, just indicate dates, keywords, or classification type to display all the relevant files.
The PlusD collection put together by WikiLeaks is updated through a variety of sources. It's updated as documents are released under the Freedom of Information Act (FOIA) or as they are reviewed and declassified by the US State Department.
As of April 8, 2013, PlusD had two million records of about a billion words, a collection covering US interventions in every country in the world.
WikiLeaks is also working to make the PlusD collection available for independent distribution. Anyone interested in obtaining or providing documents for this database can get in touch via e-mail (firstname.lastname@example.org), putting 'request' in the subject to request a document, or 'submission' to submit one.