Charles Krauthammer's final words, in a carefully but narrowly reasoned column supporting oil exploration in the Arctic National Wildlife Refuge {''Wildlife or Oil,'' op-ed, Sept. 4}, are that "if . . . one has to choose between caribou and country, it is hard to see how there is a choice." How simplistic can one be?

To his credit, Mr. Krauthammer does mention major opportunities for conservation of fuel. But hasn't he also heard about ethanol, methanol and solar energy to supplement oil? Fortunately, the figures will show that the bottom line is actually caribou and country, with plenty of both -- and fuel to spare. R. W. VAN WAGENEN Washington

Regarding Charles Krauthammer's piece emphasizing the ''national security'' of our country over the concerns of "sentimental environmentalists," a few points need to be made.

First, in asserting that the caribou herd in Prudhoe Bay has tripled since exploration began, Mr. Krauthammer fails to mention that this population explosion occurred as a direct result of the upsetting of the ecological system. We infringed on the habitat of existing predators in Prudhoe to the point where predators no longer are present to keep the herds at a sustainable level. Without doubt, we and the creatures that make up the system have not yet begun to feel the impact of this disruption.

Second, unless we as a civilization soon begin to explore alternatives to petroleum, we will find not only the long-term sustainability of the environment in question but also the long-term sustainability of our own society. CHRIS HAMMERSLA Springfield