Defense Secretary Leon Panetta has ordered the Joint Chiefs of Staff to review military ethics training in the wake of a series of investigations that involve high-ranking military officers' conduct, the Pentagon announced Thursday.

Mr. Panetta began planning for the review before recent allegations came to light against Marine Gen. John Allen, the top U.S. commander in Afghanistan, and David Petraeus, a onetime Army general and the former Central Intelligence Agency director. Still, the memo is a signal of how deeply troubled Pentagon leaders are about military misconduct.

In a memo to Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, Mr. Panetta said the ethical controversies undercut the standing of the military. The Joint Chiefs consist of the top officers of the various military branches.