ON May 18, 1993, Secretary of State Warren Christopher was asked on Capitol Hill why the United States did not condemn in the strongest moral terms the evidence of Serb atrocities in Bosnia.
His answer set out what became the basis for US government policy: ''One of the just absolutely bewildering parts of this problem,'' said Mr. Christopher, ''is that there are atrocities on all sides. ...it's different than the Holocaust ... I never heard of any genocide by the Jews against the German people. But here you have atrocities by all sides.''
His implicit message: The carnage in Bosnia is simply a repeat of old ethnic feuds -- a civil war among groups equally to blame. No one was an innocent victim deserving special help.
The problem is, as a Central Intelligence Agency report leaked to the press makes compellingly clear, none of this is true.
From photographs and what a senior US official called ''precise technical analysis,'' the CIA has determined that 90 percent of the murders and war crimes in Bosnia were conducted by Serb forces. This confirms what most journalists and witnesses have been saying: This is no civil war, but a one-sided land grab conducted through genocide and terror.
As the report also makes clear, and as the Monitor has stated consistently since 1992, the systematic aggression and ''ethnic cleansing'' in Bosnia could not have happened without orders from Belgrade and Pale.
These are enormously significant facts. Official European policy on Bosnia is founded foursquare on a view of the war as a spontaneous combustion of ethnic tensions. The US has gone along with this view on and off. If Bosnia is just a civil war, it is easy, arguably even responsible, to do nothing.
Yet the truth is otherwise. The significance of the CIA report is that, even if the West continues to allow Serb aggression, it can no longer do so under false pretenses. Someone was responsible for Bosnia; it didn't just happen. European-led negotiations on Bosnia, where British and French diplomats shuttle to Belgrade and Pale, are negotiations with those responsible for war crimes.
The CIA report may not change anything. London and Paris, and to a lesser extent Washington, have invested much capital in trying to make Serb leader Slobodan Milosevic a peacemaker. This seems a bit absurd -- like asking a kangaroo not to hop.
It won't be easy for Western officials to change their policies in response to this new information. But now, at least, more people will know what is true -- and what is not.