I left the Army years ago and their light doctrine today is certainly more sophisticated than 1992. I guess if the only goal is to maintain night adaptation of the retina, red light is supposedly the best. Also, the dimmer the light is of any color, the less degradation of night adaptation. I don't know if 10 lumens of red is better than 1 lumen of white in this regard. 10 lumens is pretty bright, by tactical field standards. 1-2 lumens is about what I'd use for tactical situations.
There are many other goals besides preserving night adaptation, however. Signalling is one. Working with night vision equipment. Not being detected by enemies. Detecting blood--a friendly's wound or an enemy blood trail. Spotting and identifying bad guys and roadside bombs. The color of the light must conform to the most important priorities at that moment. Red is not going to work well for a combat medic who is searching for bleeding wounds or signs of cyanosis. Blue/green may cause all the water features on a map to disappear. And anything but white makes spotting hidden objects really tough, since color helps us see what doesn't blend in. With what I've read about Special Forces in Afghanistan, they have discovered white is actually a better choice than red.