After you complete the game once and saving it, start a new game with the saved data. On the Navigation Deck after the battle with Olga, go up the ladder to where you would normally get the Thermal Goggles. On the center platform, before the goggles, should be a USP Suppresser on the left. You can now equip the USP with it and muzzle the gunfire for the rest of the Tanker chapter.
After completing the Tanker chapter three or four times, you can find the USP Suppresser on the navigational deck after you defeat Olga. It is found on the second floor on the lookout, near where the thermal goggles are found.