There is not one position on this among Adventists but three and are
Conciencious objection to war which is the same as the JW position.
Non Combatancy which is joining the forces as a medic or some other non combatant role.
Thirdly to join the military in a full combatant role as justification for this the case for a just war is used.
There are many Adventists right now risking there lives in Irak.
Adventists such as Desmond Doss a non combatant made great contributions to the forces and received the highest awards for his efforts.
Adventists also support those who join the forces in full combatancy roles and support the forces with there clergy.Admiral Black is cheif of clergy in the US Navy and is a Seventh Day Adventist.