In a speech in San Francisco, Gates spoke of "anxiety" over the future role of the service after nearly a decade of fighting on land in Afghanistan and Iraq. He said some feel the Corps has "become too heavy, too removed from their expeditionary, amphibious roots and the unique skill sets those missions require." Though many Marines are battle-tested, some "may never have stepped aboard a ship."
Gates did not say Thursday whether the force structure review, to be led by Navy Secretary Ray Mabus and Gen. James Amos, the incoming Marine commandant, will result in "the few" becoming fewer after bulking up in recent years. But in a separate session with sailors aboard the destroyer USS Higgins, the Pentagon chief said the Corps had "gotten too big" and would be trimmed.
That prediction is in line with a larger overhaul that Gates detailed this week. It will involve belt-tightening across all the services and at the Pentagon to wring out $100 billion in savings over the next five years.
The days of storming Iwo Jima are long gone. Marines still belt out "From the Halls of Montezuma to the Shores of Tripoli," but as they learned in Somalia, where journalists beat them ashore in Mogadishu, times have changed.
Marines deployed aboard Navy ships remain the go-to ready forces in a crisis. Unlike the Army, they are lightly equipped to move quickly ashore by sea or air to conduct evacuations, relief operations or initiate combat. Traditionally the first in, they also are usually the first out, replaced after a few weeks by heavier Army troops trained for the long haul.
That "unique ability to project combat forces from the sea under uncertain circumstances -- forces quickly able to protect and sustain themselves -- is a capability that America has needed in this past decade and will require in the future," Gates said.
About 1,000 Marines flew in to the Afghan desert from ships more than 400 miles away in the Northern Arabian Sea to start the war against the Taliban in October 2001. Almost nine years later, though, 20,000 Marines are still fighting in that landlocked country, doing a job nearly indistinguishable from their soldier brethren.
"These warriors are writing a new chapter in the Marine Corps roll of honor with their blood and their sweat," Gates said.
Despite the Corps' storied history as the Navy's on-board landing force, the Pacific campaign of World War II was the only period in history when the service focused almost exclusively on amphibious assaults. The last major combat landing was during the Korean War at Inchon.
"It is proper to ask whether large-scale amphibious assault landings along the lines of Inchon are feasible," Gates told an audience that included retired Marines. "New anti-ship missiles with long range and high accuracy may make it necessary to debark from ships 25, 40 or 60 or more miles at sea."
Beach landings have become so rare that the Marines made headlines in June when the Corps put on an amphibious training exercise at California's Camp Pendleton.
Meanwhile, military observers questioned Gates' concern about blurring the lines between soldiers and Marines.
"They are a second land army -- and a third air force, by the way. That's not necessarily a bad thing. It provides a competing way of operating. What could be more American than such a competition?" said Thomas Ricks, a senior fellow at the Center for a New American Security and author of "Making the Corps," about how Marines inculcate their culture at boot camp.
"I wouldn't make a lot of changes to the Marines right now. They tend to be very handy in the first phases of wars -- Guadalcanal in World War II, the Pusan Perimeter in Korea," he added. "I'd make bigger changes in the Army, really taking seriously the mission to train foreign security forces. And I'd look for really big savings more in the support areas than in the teeth area."
But Andrew Bacevich, a national security expert at Boston University and a graduate of the U.S. Military Academy at West Point, said the Marines have become an "example of the redundancies that permeate our defense establishment. ... Redundancies can be good as long as you can afford them. We no longer can."
Anthony Cordesman, a defense analyst at the Center for Strategic and International Studies, cautioned against too much tinkering with an organization established by the Continental Congress in 1775.
"The reality is, when you have one of the most successful combat units in the world," he said, "you do not conduct fascinating social experiments to see if you can transform it into something else."