It is a rare confluence of tenure calendars and personal calculations, coming midway through Mr. Obama’s first term and on the heels of an election that challenged his domestic policies. His choices could have lasting consequences for his national security agenda, perhaps strengthening his hand over a military with which he has often clashed, and are likely to have an effect beyond the next election, whether he wins or loses.
That is all the more reason that Mr. Obama’s choices are certain to face scrutiny in a narrowly divided Senate, whose Republican leadership has declared itself intent on defeating him.
Defense Secretary Robert M. Gates has said he plans to retire next year, while the terms of four members of the Joint Chiefs of Staff are scheduled to end: Adm. Mike Mullen, the chairman; Gen. James E. Cartwright, the vice chairman; Gen. George W. Casey Jr., the Army chief; and Adm. Gary Roughead, the chief of naval operations.
Andrew J. Bacevich, a retired Army officer who is a professor of history and international relations at Boston University, said this round of replacements, coming after two years of difficult and sometimes intense wrangling over how to carry on the war in Afghanistan, “is particularly important, and is likely to prove particularly difficult.”
“The challenge facing the president,” Mr. Bacevich said, “will be to identify leaders who will provide him with disinterested advice, informed by a concern for the national interest, and, in doing so, to avoid either the appearance or the reality of politicizing the senior leadership.”
At the top of the new pantheon of military power, the president needs a heavyweight to succeed Mr. Gates, an unexpected holdover from the