Gen. Martin Dempsey is taking over as chairman of the Joint Chiefs of Staff, the first Army officer in 10 years to hold the nation\'\'s highest military post. He is being sworn in Friday as successor to Navy Adm. Mike Mullen, who is retiring, according to a media report. Even before taking over, Dempsey made it clear that he differs with Mullen on one important issue: the threat posed to national security by a growing national debt. At his confirmation hearing, Dempsey was asked whether he agrees with Mullen\'\'s assertion that the debt crisis is the single biggest threat to national security. Dempsey said U.S. power is derived in equal measure from three strengths: military, diplomatic and economic. Dempsey believes the United States cannot be successful in managing its national security and international affairs without asserting influence through a combination of a powerful military, an effective diplomatic corps and a sound economy. His will be among the key voices in recommending how to cut hundreds of billions of dollars from the defense budget over the coming decade.