They drove up to a base gate in a truck and claimed to be Amazon subcontractors making a delivery, a Marine spokesman said.
The Air Force is investigating the death of a 28-year-old airman found unresponsive on Andersen Air Force Base, Guam, on Wednesday.
The Pentagon is sending more troops and equipment to the Middle East in anticipation of a possible Iranian attack on Israel.
Guardsmen are facing more hostility downrange than they have in years.
