Kill assists count towards the requirements for military support.
Team Player is a first-tier perk, unlocked at Level 10 after full specialisation customisation is unlocked and is available for 5,000 credits, along with Sharpshooting. When equipped, every kill assist is one point added towards your kill streaks. This perk is very useful as the Intervention specialisation allows you to get full XP for a kill assist. Couple this with a shotgun or sniper rifle with explosive rounds and you're all set.