That's somewhat true, in that your "heat" level goes up to level 1 as soon as you cause the slightest bit of trouble. Guards will come and now you're left with the option of killing them all (which can be done) or running (flying) away to cool of your heat level. However, the enemies don't just spawn over and over...they're limited to whoever is at the facility/location in question. Although, if your heat level is high enough, they will hunt you down with any nearby vehicles or even helicopters. On the upside, it doesn't take very long to cool off - - just jump in a vehicle or aircraft or parasail away. They'll leave you alone after a minute or two.

