Latest "espionage" stories
The 22-year-old sailor was one of two sailors arrested last week in California and accused of providing military information to China.
China claims it was a civilian balloon used for meteorological research but has refused to say to which government department or company it belongs.
A federal judge questioned how much knowledge of the documents and their contents a defendant would need to have to be proven guilty under U.S. statute.
By Jessie Bur