http://www.guardian.co.uk/Iraq/Story/0,2763,957829,00.html

The USA is stepping up pressure on smaller countries to sign up to
sign bi-lateral deals that exempt American citizens from
prosecution for Genocide, Crimes Against Humanity, and War Crimes
outside the USA (several of which aren't recognised as crimes under
US law).

This is part of George Bush's fierce opposition to the soon-to-be
functioning International Criminal Court (the Clinton
administration had initially signed up to it, but never ratified
it). The main basis of their argument is that International Laws
that they don't approve of, are a threat to US national
sovereignty, and that cases against US citizens might be
politically motivated (unlike American policy, which is almost
always economically motivated).

Thirty countries have so far signed Impunity deals with the USA,
and this weekend Bosnia has become the latest country to do so.
 http://web.amnesty.org/pages/int_jus_icc_imp_agrees

There have also been reports that they International involvement in
the security and rebuilding of Iraq could be dependent on signing
such deals. (who in their right would invite possible law-enforcers
to the scene of their crime).
 http://www.goasiapacific.com/news/GoAsiaPacificBNP_857527.htm