Mark joined the Department of Defence in the mid-1990's following a career as a theoretical physicist.
During this time in Defence, he was deployed as a civilian truce monitor to Bougainville in 1997 and as political-military adviser to the INTERFET Commander in 1999.
In 2002, Mark joined ASPI.
Mark's research interests include strategy, defence economics and defence industry policy.
In November 2005, Mark was a member of the Ministerial directed review of military recruitment and retention, and in 2006 he was a member of a review team looking at Australia defence industry policy. In 2008 and 2009, Mark was a member of the ministerial advisory panel for the Defence White Paper.