In this challenge, your enemies are scientists with enhanced health, health regeneration and weapon damage. This challenge can be quite the challenge as they are hard to take out, so use a powerful weapon against them.
Alternately, use a Tank with Ricochet to run past the scientists entirely and grab the intelligence. The killstreak is however hard to get due to the enhanced scientists, so play conservatively and only fire if they are near.
Tear gas is quite effective, and, suprisingly, a katana is actually very useful due to its sheer damage, and moderate attack rate, but the player needs to be skilled at dodging and resisting fire.