*Spoilers Ahead*
One good mission for this is in Moskow, Molotek. To do this you have to interrogate Brayko to learn that Sergei Surkov is still in the weapons business. After this information Molotek will unlock as your final mission in the Russia chapter. This mission is VERY easy but only if you have your stealth skill on maximum level. Don't attack anyone, just run & hide. When you confront Surkov you MUST make a deal with him (otherwise his bodyguard will attack you = red arrows).