WEST POINT, N.Y. — If Douglas MacArthur or Ulysses S. Grant went to the U.S. Military Academy today, they might be testing their defensive skills hunched in front of a computer screen.

A team of caffeine-fueled cadets is spending long days this week in a computer lab trying to fend off threats cooked up by experts at the National Security Agency. The annual Cyber Defense Exercise running through Thursday will determine which of the five service academies can create computer networks that can best withstand the four-day barrage.