Ok explain this (from http://www.bartleby.com/65/wa/warcrime.html):

Under the G. W. Bush administration, the United States opposed
implementation of the [International Criminal Court] treaty , out of
fear that American officials or military personnel might be arrested
abroad on baseless charges. In May, 2002, the United States repudiated
its signing of the treaty and indicated that it would refuse to
cooperate with the court. The U.S. government subsequently insisted
(2002, 2003) that U.S. forces used as UN peacekeepers be exempted from
prosecution by the court, and in 2003 it suspended military aid to
nations that did not similarly exempt U.S. citizens serving within their
borders.

In 2004, following the Iraq prisoner abuse scandal, the United
States was unable to secure a further exemption from the United Nations.