state system, realists encourage leaders  to act in ways based on suspicion, power,  

and force. As a result, realism might  be viewed as a self-fulfilling prophecy.

Realists, on the other hand, believe that leaders  face endless constraints and limited opportunities  

for collaboration. As a result, they have few  alternatives for escaping the realities of power  

politics. For a realist, facing the reality  of one's situation is prudent and rational.

Realists also often argue that realism  actually encourages the leader to be  

extremely cautious when deciding where and  when to use military power and only use it  

when it serves your national interests. For  example, the US invasion of Iraq in 2003,  

undertaken as part of the Global War  on Terror, was opposed by most leading  

realists in the US as a misuse of power that  would not serve the US national interests.