Why transcripts of Trump's calls with heads of state are so hard to get

A US intelligence official filed a whistleblower complaint citing a July 25 telephone call in which Trump asked Ukrainian President Volodymyr Zelenskiy to investigate Biden and his son Hunter. The whistleblower says this wasn't the first time under the Trump administration that a telephone conversation record was placed into a codeword-level system to protect politically sensitive information. Tom Blanton of the National Security Archive spoke to The World about the "codeword-level" system.