A member of the House Armed Services Committee wants an explanation for why the next Arleigh-Burke class guided-missile destroyer will be named for a politician instead of a war hero.

Rep. Duncan Hunter, a Republican from California and a Marine Corps veteran, sent a letter to Navy Secretary Ray Mabus Wednesday, asking him to explain his decision to name DDG-120 after former Sen. Carl Levin, a Democrat from Michigan, who retired last January after 36 years in office.

The letter was first reported by Defense News.

Hunter cited July 2012 Congressional Research Service report to Congress that showed that destroyers are traditionally named for deceased members of the Navy, Marine Corps and Coast Guard, including former secretaries of the Navy.

The report, however, notes that exceptions to ship-naming rules can be made by the secretary of the Navy.

"A secretary's discretion to make exceptions to ship-naming conventions is one of the Navy's oldest ship-naming traditions," the report found, noting that exceptions in order to name ships for presidents or lawmakers happened often enough to constitute a "special cross-type naming convention."

"It is my firm belief that Senator Levin served this country honorably as a member of the United States Senate and was a strong advocate for our men and women in uniform," Hunter wrote.

However, the congressman added, "it is important that the Navy adhere to its own ship naming rules and take every effort necessary to avoid politicization of this process."

Other recent exceptions to the destroyer-naming tradition have included the Thomas Hudner (DDG-116), the Paul Ignatius (DDG-117), and the Daniel Inouye (DDG-118).

Hudner, a Navy Medal of Honor recipient, and Ignatius, a former Navy secretary, are both still living. Inouye, who died in 2012 while a sitting senator, was a Medal of Honor recipient from the Army.

A spokesman for Mabus, Capt. Patrick McNally, declined to comment on Hunter's letter.

However, McNally told the Washington Times earlier this week that "[Mabus] names ships for American heroes and considers Senator Levin's long commitment to the nation worthy of recognition ... The naming conventions are guidelines set by the secretary. He can deviate from them if he desires."

A new CRS backgrounder released to Congress earlier this month and obtained by Military.com showed it's historically very rare to name ships after living individuals, though Mabus has often gone against traditional practice.

Roughly 18 ships have been named for people who were still alive when the ship name was announced, the report found. Seven of the 18 have been announced since January 2012, all seven under Mabus' tenure as Navy secretary.

The decision to name a destroyer for Levin may not find significant opposition in the Senate, however. The news came up during an April 6 hearing on shipbuilding programs before the Senate Armed Services Committee's subcommittee on seapower, and was warmly received.

The committee's chairman, Sen. Roger Wicker, a Republican from Mississippi, called the information "pleasant news" and Sens. Kelly Ayotte, a Republican from New Hampshire, and Angus King, an Independent from Maine, both praised Levin and expressed enthusiasm for the decision.

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.