President Bush is nearing an announcement on his choice for the nation's top military officer. Aides indicate he could name a new Chairman of the Joint Chiefs of Staff later this week.

It may be the best kept secret in the Bush administration. Secretary of Defense Donald Rumsfeld said last Friday that the President has chosen the next Chairman of the Joint Chiefs of Staff. But Mr. Bush is keeping quiet about the selection, and aides are providing few clues.

There was speculation the announcement might come Monday when Mr. Bush addressed a convention of military veterans. Officials now indicate it is unlikely before Thursday.

The chairman of the Joint Chiefs is, by law, the principal military advisor to the President. The front-runners for the job are believed to be Navy Admiral Vern Clark and Air Force General Richard Myers. The last three officers to hold the post came from the army.

The current chairman, Army General Henry Shelton, completes his second two-year term on September 30.