Historically, Western armies have struggled with the task of training, advising and assisting host-nation security forces to defeat irregular adversaries. This is part and parcel of their broader problem with irregular conflict. Conventional military forces are designed for combat against counterpart forces of other states, and they have often been unable to adapt to the demands of irregular warfare when their opponents refused to obligingly fight them in the manner they had prepared for. Perhaps in no area of warfare have Western armies been less able to adapt than in the area of training and advising indigenous forces -- and in no area has that lack of adaptability been more costly.
Although the U.S. Army was the planet’s most successful land power in conventional war in the 20th century, it has struggled with the challenge of irregular warfare from Vietnam through the wars in Iraq and Afghanistan. For a host of reasons, ranging from America’s conventional military superiority to globalization and resource depletion, the wars we will actually fight in this century are likely to look more like the small wars in which we have struggled than like those, such as Desert Storm, in which we have prevailed comparatively easily. And the most important way the U.S. Army can prevent as many of these wars as possible, and prevail in the ones that it must actually fight, is by developing the capability to train host-nation security forces.