This objective appears after interrogating the first pusher. There are two targets for this objective.
Raid Mansion Drug Delivery
The resupply boats are located in the docks at the back of the mansion. No need to go stealth here; however the best spot to hit them is from the docks. Make sure that you kill the sentry first since there’s only one in the entire area. The others, you can overpower in a gunfight.
Raid Boathouse Drug Delivery
It’s easier to circle around the boathouse and kill the guard outside then lure the sentry to an ambush. Once inside, you can now throw a grenade in the middle of the enemies playing cards on the table to kill them all at once. Just keep using your intel view to keep track of the enemy movements.