ISIS has a strong affiliation with al Qaeda and the past history of the 9/11 terrorist attack; The United States is a leading country in the fight against terrorism. The United States' strategy in the war on terrorism is heavily influenced by realist theory. Globally, terrorism is not seen as a simple criminal action but as a declared war on humanity. This can be linked to the realist view of anarchy that any aggression is war and defense against it is the same thing or simply going to war. Therefore, the United States views ISIS's association with al Qaeda as a national security threat and may launch a preemptive war in response. If fighting terrorism means destroying ISIS, then the United States should be ready to accept the consequences and financial destruction which raises the moral question.