The United States is reviewing indictments of Bosnians and others accused of war crimes to target the worst offenders for capture, the top U.S. envoy to the region says.

"We intend to stay very focused on this," Ambassador Robert Gelbard said Wednesday at a Bosnia forum organized by the United States Institute of Peace, a federally financed think tank.Just returned from the region, Gelbard said more Croatian and Bosnian-Serb authorities are cooperating in turning over suspects or allowing their capture by NATO peacekeepers, who are instructed not to go after suspects whose cases aren't likely to be prosecuted.

"The United States believes that a significant number of indictments will not stand up in court," Gelbard said. "We will not risk the lives of any soldiers or anybody else to try to apprehend indicted war criminals if we believe that the cases are weak."

Under NATO leadership of Gen. Wesley Clark, Gelbard said the peacekeeping force, SFOR, has become selectively aggressive in seizing accused war criminals or persuading them to turn themselves in.

"We are prepared (to use), and have used already, any and all available options to ensure the indictees get to The Hague," where an international war crimes tribunal is operating, he said.

The third Bosnian Serb suspect to surrender to U.N. custody for trial arrived Tuesday in the Netherlands after he was informed he was a target of the NATO troops, Gelbard said. That makes more than two dozen suspects in custody, compared with a half-dozen last spring.

In late January, U.S. soldiers led their first operation in Bosnia to capture a war crimes suspect as part of a shifting strategy for NATO and the Clinton administration, which had long contended it wasn't SFOR's job to go after war criminals.