A need (or perceived need) for leaders to make decisions quickly.
Potential costs in human suffering if their decision results in war.
Due to the large amount of information, decision makers do not know what information to ignore or believe.
Faulty and incomplete data
Intelligence information about your opponent (strength, weakness, options, etc.) is usually limited and inadequate. Then you turn to more simpler means of data.
Decision makers see themselves as having a limited range of options, whereas your opponent is perceived as having a wide avenue of options.
Short-term over long-term
Decision makers tend to shift toward the short-term effect as apposed to the long-term effects due to stress and patience.
Even though the situation may not be entirely unexpected, an element of surprise is often involved, so most crises appear to the decision makers as needing to be resolved on the spot, without benefit of preanalyzed scenarios.
Decisions of import must often be made under conditions of sleep deprivation and sometimes under great anxiety, bordering on panic.