In the first hostile area of mission 5, you are armed with only a silenced pistol and must sneak past enemies to place two bombs. Follow the video for an easy path through the stealth section. The trophy / achievement unlocks immediately when planting the second bomb.
Here is a video guide with English commentary!
Here is a playlist of guides for this game!
https://www.youtube.com/playlist?list=PL-HeW6XkKdUKe25WzwEqI...