text: FM 7-100.1________________________________________________________________________________
  History has proven that battlefield victory does not always go to the best-trained,
  best-equipped, and most technologically advanced force. Victory often goes to the
  side that most wants to win, needs to win, and is willing to sacrifice to do so.
  Time
  In most cases, potential opponents of the United States view time as being in
  their advantage. When U.S. forces have to deploy into the area over long time
  and distance, the opponent can use this time to adjust the nature of the conflict
  to something for which the U.S. forces are not prepared.
  First, the opponent will try to control the entry of U.S. forces into the area. If ac-
  cess control fails, the enemy still has the opportunity to oppose lightly equipped
  U.S. early-entry units and try to prevent full deployment of the rest of the force.
  The opponent will try to speed up the tempo, to rapidly defeat its local or re-
  gional enemy or to defeat U.S. early-entry forces before the United States can
  deploy overwhelming military power. If that fails, the opponent will try to pro-
  long the conflict and to outlast the U.S. will to continue.
  Military Capabilities
  Military capabilities of a nation-state or non-state actor are measured in relative
  terms, in comparison to the capabilities of other actors against which they might
  be applied. Most of the military forces in the world continue to operate in conven-
  tional ways, which remain sufficient against other local and regional actors.
  However, once the United States becomes involved, these same military forces
  may have to use adaptive or asymmetric approaches. Various nations and
  other foreign entities around the world study the United States and its military
  forces. They generally view the United States as a major power—the world’s only
  superpower—with an overall advantage in technology and warfighting capabil-
  ity. Despite these strengths, other actors see some weaknesses that they may be
  able to exploit. They can use these perceptions as a guide to optimizing the effec-
  tiveness of their own forces and to find ways to negate current U.S. advantages.
  Military capabilities may be the most critical and the most complex variable that
  affects military operations. However, the military variable does not exist in isola-
  tion from the other variables that help determine the overall OE. It interacts
  with the other variables, and all the other variables can affect military capabilities.
  Potential enemies can use any or all of these factors against the Army as it tries to
  accomplish its missions in various parts of the world or in various training environ-
  ments.
  REAL WORLD
  In the real world, the COE is the entire set of conditions, circumstances, and influ-
  ences that U.S. Armed Forces can expect to face when conducting military opera-
  tions to further the national interests of the United States, its friends, and allies.
  The COE is “contemporary” in the sense that it does not represent conditions that
  existed only in the past or that might exist only in the remote future, but rather
  those conditions that exist today and in the clearly foreseeable, near future. This
  COE consists not only of the military and/or paramilitary capabilities of potential
  real-world adversaries, but also of the manifestations of the ten other variables that
  help define any OE.