“What are we supposed to use — harsh language?”

Well, with LRAD, yeah, that would be pretty effective.

LRAD [Long Range Accoustical Devices] is a breakthrough long-range hailing and warning, directed acoustic device that is designed to determine intent, change behavior, and support various rules of engagement. With LRAD, a sentry can issue a focused verbal challenge with instructions in excess of 300 hundred yards, and follow up with a warning tone to cause behavior change. Recorded messages can be selected and delivered over LRAD in multiple languages.

Basically consider it a very focused, extremely loud, megaphone.

Dubbed “The Sound of Force Protection” in a company brochure, the devices can broadcast sound files containing warning messages. Or they can be used with electronic translating devices for what amounts to “narrowcasting.”
If crowds or potential foes don’t respond to the verbal messages, the sonic weapon, which measures 33 inches in diameter, can direct a high-pitched, piercing tone with a tight beam. Neither the LRAD’s operators or others in the immediate area are affected.
The devices “place distance between the Marine and their threat, giving him/her more time to sort out a measured and appropriate response,” Lt. Col. Susan Noel, force protection officer for the 1st Marine Expeditionary Force, said in an ATC statement announcing the contract.
Gruenler compares the LRAD’s shrill tone to that of smoke detectors, only much louder. It can be as loud as about 150 decibels; smoke detectors are in the 80 to 90 decibel range.
“Inside 100 yards, you definitely don’t want to be there,” said Gruenler, adding that the device is recommended for a range of 300 yards or less.

150 dB is about 10 dB higher than an aircraft jet engine on take-off. Yeah, that would be pretty discouraging.

(via BoingBoing, too)