Elie Wiesel-"The Perils of Indifference"-Why does he think indifference on the part of America endangers the entire world?

Wiesel draws upon his own experience as a survivor at Buchenwald, one of the Nazi death camps, to prove the argument that American indifference endangers the entire world.  He makes the valid assertion that it was the action of American troops that stopped Hitler, ended the Holocaust, and freed the survivors, like Wiesel himself:  "And now, I stand before you, Mr. President- Commander in Chief of the army that freed me, and tens of thousands of others- and I am filled with a profound and abiding gratitude to the American People."  In the speech, Wiesel asserts his belief that indifference ("not caring") would have not freed him from the hell of the Holocaust, and serve to aid the aggressor:

Indifference elicits no response. Indifference is not a response.

Indifference is not a beginning, it is an end. And, therefore, indifference is always the friend of the enemy, for it benefits the aggressor -- never his victim, whose pain is magnified when he or she feels forgotten. The political prisoner in his cell, the hungry children, the homeless refugees -- not to respond to their plight, not to relieve their solitude by offering them a spark of hope is to exile them from human memory. And in denying their humanity we betray our own.

Notice again, the argument being articulated here.  It is not merely the absence of action which is wrong.  It is the fact that absence of action is a silent nod to the aggressor, it is complicity.  The irony of the situation is not lost on a survivor like Wiesel:  America, as well as other nations in the Europe, knew very well what Hitler was proposing, why these nations' indifference to Weimar Germany's struggles enabled Hitler's rise to power, and that the Nazis represented a force of doom to millions of Jewish people and millions others.  It was indifference that caused the Holocaust.

Wiesel concludes by demanding the America exercise the same moral authority it did during the Holocaust, in the situations such as Kosovo or Rwanda.  Indifference or isolationism is not an appropriate response to evil, and Wiesel's argument is that American indifference assists the aggressors or perpetrators of such evil, endangering the entire world.