There are 4 requirements for this acheivement :
- During the mission "Intercept Surkov at US Embassy", after you first meet with Surkov, you'll climb up a ladder, in the next room/hallway you'll have a firefight which can distract you and make you miss Surkov's computer. Hack it.
- During the following mission, "Contact Surkov at Moscow Office" dont choose the PDA responses at all, or the convo will be shortened and you will be presented to his bodyguard sooner than usual.
- When you defeat Konstantin Brayko, let him live long enough for him to give you all the additionnal info he has on Surkov. That will unlock the real final Moscow mission (along with hacking his computer). When he's done and begs for his fife, you can then kill him if you want.
- Do NOT leave Moscow before you attempt the next mission ("Prevent Surkov's escape"), or else that extra mission will disappear. It's either a bug, or you were too late and he escaped. When you meet with Surkov again, choose to attack him. When you catch up with him, execute him.
Bonus info (credits goes to Alita360) :
1) make a savegame just when you arrive at molotek, so after getting this chievo, you can reload that save and get the other chievo for making an alliance with Surkov (only available if you befriended Grigori enough ; check the Russian Alliance acheivement solution)
2) when proceeding for this chievo, attack him when you finally face him, he'll send the bodyguard on you. which is a tough bone
3) when you intercept him finally before the helicopter, chose to execute him and shortly after the chievo will pop.