WASHINGTON (AP) - The man often called America's top military officer, the most powerful person in uniform, actually commands nothing. No tanks, no planes, no ships, no troops.
His voice carries great weight, but he gives no combat orders.
He is chairman of the Joint Chiefs of Staff - adviser to presidents, advocate for troops and their families, strategic thinker, and occasionally a political punching bag. He stands at the apex of the military hierarchy, and the role has grown in influence and public prominence, yet it remains arguably one of the least understood. In the view of some who have held the job, this disconnect has made the chairman more vulnerable to political swipes from all sides.
Since the position was established in 1949, 18 men have been chairman of the Joint Chiefs. Nine were Army generals, four were Navy admirals, four were from the Air Force and one was a Marine.
Pending an expected Senate vote to confirm him this month, Gen. Joseph Dunford will be the next chairman. Currently commandant of the Marine Corps, Dunford is expected to take over Oct. 1 for Gen. Martin E. Dempsey, who will retire after a 41-year Army career.
The chairman is the public face of the military, but he is not in the formal chain of command linking the president to his commanders in the field.
Dempsey, who is completing four years in the job, has said it reminds him of entering the Army as a lowly second lieutenant.
"I felt like I had enormous responsibility but I didn't have very much authority; that's kind of what it's like being chairman," he said in January 2014.
By law, the chairman presides over the Joint Chiefs of Staff - the top officers of the Army, Navy, Air Force and Marine Corps, and since 2012, the National Guard. Collectively they form a sounding board for commanders of key combat organizations such as U.S. Central Command, and for the president and the secretary of defense.
The chairman advises the president and the defense secretary on military threats, risks and options, but he bears no obligation to toe the political line of the White House. Yet this proximity to power can make the chairman a ready target of political attacks.
Sen. John McCain, R-Ariz., for example, has accused Dempsey of being the Obama administration's lapdog.
Dempsey brushes off such criticism, calling it wrong-headed but not surprising.
"It has happened to every chairman since I've become aware that there was a thing called the chairman of the Joint Chiefs of Staff," he said in an interview. He attributes the jabs partly to a misunderstanding of the role of the chairman.
Dempsey says the chairman is supposed to be an adviser, not an advocate for any strategy or policy that the president may be considering. He sees his role as explaining to his civilian bosses - and to members of Congress - which military options are feasible and assessing their risks and costs. However, it's up to civilian leaders to set policy goals and to decide whether to undertake any military option in pursuit of those goals.
"There's actually an acronym: pol-mil. I'm the dash," he says. "I'm the guy that lives in between the policy objectives as articulated by our elected leaders and the military activities to achieve it."
At times the chairman's advice is rejected. In 2013, for example, Dempsey acknowledged under questioning by McCain that he had supported a CIA proposal to arm rebels against the Syrian government. President Barack Obama rejected it, although last year he initiated a $500 million plan to train and equip Syrian rebels to fight Islamic State militants.
Peter Pace, the retired general who was the first Marine to hold the job, said he never shaped his advice to President George W. Bush based on politics. However, politics shaped his term as chairman. Pace is seen by some as a political casualty of the war Bush started in Iraq in 2003 while Pace was the vice chairman. Bush's defense secretary, Robert Gates, announced in June 2007 that he advised Bush not to re-nominate Pace to a second two-year term as chairman because it would create a "divisive ordeal" in the Senate over the decision to invade Iraq and the mistakes that followed.
"Not being re-nominated was very much a political reality," Pace said in an interview.