Here is the full list of all 10 Strike Team Gladius achievements worth 1,000 gamerscore.
Complete the first mission of the campaign.
Kill your first enemy in combat.
Kill 100 Brood Warriors
Defeat the aliens in the jungle campaign.
Kill the last of the portal guardians and seize control of the portal to the alien home world.
Kill the templar.
Complete the single player campaign.
Kill the Dominator Leader.
Finish the desert campaign on Extreme difficulty
Kill the alien commander leading the resistance to the orbital assault.