David Franklin Slater, a 63-year-old civilian employee of the US Air Force, has been charged with allegedly conspiring to transmit and transmitting classified information relating to national defence between February and April 2022.

Prosecutors have published some of the messages exchanged by the pair. In one, the purported woman writes: “You are my secret informant love! How were your meetings? Successfully?”

In another, she says: “You have a job in the Operations Center today, I remember, I’m sure there is a lot of interesting news there?”

At one point, she thanks him for telling her about two US officials travelling to Kyiv.

Assistant Attorney General Matthew G. Olsen of the US Justice Department’s National Security Division said: “The Department of Justice will seek to hold accountable those who knowingly and wilfully put their country at risk by disclosing classified information.”