Here is the full list of all 21 World In Danger achievements.
Completed all story missions
Defeated Machine-gun Ali
Defeated Miss Dynomite
Defeated Red Wolf
Fought againts Sako
Defeated Blaser
Defeated the traitorous recruit and his airsupport
Defeated Super powered duo
Defeated R.A.P.T.O.R.
Finished Boss Attack Mode on Ironman setting
Get S-rank in Boss Attack Mode
Speak to every person in free-roam mode once
Listen to all conversations in free-roam mode
Find Marco’s hiding spot 5 times in free-roam mode
Find and rescue all 7 smuggled animals hiding in various levels
Get S-Rank on a single mission
Get S-Rank on a boss mission
Get S-Rank for every mission
Beat a boss mission using only a handgun
Complete a mission with every playable character
Earn all codenames / achievements