Half the time it is the nighttime and the things are in IR https://news.ycombinator.com/item?id=47000051 . You may still try to camouflage and decrease your IR visibility - stealth planes try to do it, and there are some IR-decreasing covers for tanks and people.

The night time hunt using IR is widely practiced today in Ukraine and even was widely practiced by US and USSR in Afghanistan and Iraq as surroundings gets cooled down and cars, people and say donkeys used to transport weapons in mountains become highly contrast against the surroundings and thus easy to spot visually and to lock IR seeker of a weapon. Saddam used USSR anti-ship missiles, old even then, to attack Iran oil storage tanks at night as the missiles were easily able to lock on that large bright IR emission of the tanks still hot from the day against the cold night desert.