DSDA is responsible for the supply of munitions, tanks, jets and other equipment from point of purchase to troops.
Trimedia managing director Simon Elliott said: ‘DSDA wants people to know it is a key component that enables the MoD to carry out the Government’s wishes.’
He said the campaign’s timing was not down to the organisation being under any particular threat but was a recognition of its need to be more proactive.
The campaign will target MPs and parliamentarians with an interest in defence.
Trimedia beat Weber Shandwick and Lockwood Lewis Associates in a competitive pitch to secure the 12-month contract, which includes responsibility for media relations as well as a public affairs programme.