The U.S. Navy has finally and officially given up on long-standing plans to expand the fleet from today's 285 major warships to 313 sometime in the next couple decades. Instead, the expansion will halt at 306 large ships, according to the latest Navy planning document, obtained by Defense News.

Officially, the lower goal is a result of careful analysis of U.S. strategy, the needs of regional commanders, ship service-life and the capabilities of the shipbuilding industry. (Navy officials anticipated the shrinkage last year.) "A 306-ship combatant force [is] the current requirement to enable [the] Navy to deter and respond to crises and war," the sailing branch asserted. As the Navy sees it, it can do that by buying fewer surface warfare ships and more logistics vessels, as well as by pre-positioning warships in allied ports.

Unofficially, there is another huge factor: money. For all the talk inside the Pentagon about strategy driving budgets and not the other way around, the Navy is anticipating shrinkage right as it also anticipates playing a larger role in U.S. national security.

The seven-ship reduction is a "reflection of budget realities," Eric Wertheim, author of the definitive Combat Fleets of the World, tells Danger Room. Pentagon budgets have been steadily flattening for two years. And automatic spending cuts, known as sequestration and mandated by the 2011 Budget Control Act, could slice another 10 percent off the military's top-line starting in March -- assuming the White House and lawmakers don't reach a deficit-reduction agreement to avert sequestration.

Any way you cut it, there's not a lot of extra cash padding the Pentagon's wallet.

Ships ain't cheap. A single aircraft carrier can cost $12 billion -- and the Navy intends to keep 11 of them. Destroyers, the workhorses of the fleet, range in price from $2 billion to $4 billion. The Navy projects keeping more than 80 of them in service. Even the Littoral Combat Ship, the much-maligned "inexpensive" near-shore fighter, sets back taxpayers around $600 million each for more than 50 copies.

To build all these ships at a pace of between seven and a dozen per year, the Navy gets only $15 billion or so annually from Congress. With unpredictable labor and materials costs, ship prices can rise unexpectedly. The Congressional Budget Office predicted the Navy's shipbuilding plan would end up costing 19 percent more than the Pentagon's own rosy estimates.

The small decrease in the fleet's future growth could help close the budgetary gap -- assuming budgets don't fall further. That reflects more realistic planning on the part of the Pentagon.

What the cuts do not reflect are any expectations of a more peaceful world or a reduced demand for Navy patrols near Iran, off the pirate-infested African coast or in the tense China Seas. The world's not really getting any less dangerous, Wertheim adds. "I don't see much on the global scene that has suddenly changed in the past five years so that now we need 306 instead of 313 [ships]."

In other words, the new, smaller future fleet is budget-driven, not strategy-driven. Wertheim calls that "the tail wagging the dog."

The tail's been wagging for some time. After sticking with the 313-ship goal since 2005, a year ago the Navy began signalling a smaller expansion. The sailing branch's 30-year shipbuilding plan released last March projected a long-term fleet of 310-316 major warships, including aircraft carriers, cruisers, destroyers, submarines and Marine-hauling amphibious ships. And within a couple months, Chief of Naval Operations Jonathan Greenert was making vague references to maintaining a fleet of "approximately 300" ships.

The overall reduction in planned warship numbers is not surprising. What's more surprising is the precise mix of ships the Navy is now anticipating. As expected, aircraft carriers and submarines are left untouched, but the new planning document does cut gun- and missile-armed surface warships while adding a fairly large number of support ships. Usually, the military branches protect their most glamorous weaponry, instead trimming the less sexy support forces whenever there's a cash shortfall.

This time, the desired number of destroyers and cruisers drops from 94 to 88, mitigated somewhat by the forward basing of four destroyers in Rota, Spain. Homeporting ships overseas means they don't have to spend time sailing to and from deployment zones, allowing fewer ships to cover the same territory.

The planned fleet of Littoral Combat Ships (LCS) drops only slightly from 55 to 52, despite analysts' predictions that production of the smaller ships might be halved, and Pentagon testing projections that the ship can't survive combat. Wertheim chalks up the LCS force's survival to the personal advocacy of Navy undersecretary Bob Work and other senior leaders who are ardent defender of the speedy, relatively lightweight vessel. Work "believes in LCS," Wertheim says.

While armed ships get cut under the new plan, logistics vessels enjoy a big boost, going from 46 to 52. The expanded support force includes more cargo ships, electronic surveillance vessels and the Navy's planned new fleet of oilers -- a type of sailing gas station for other ships. An extra spy ship allows for "sustained operations and crisis response in the Pacific," the Navy explains.

Other extra logistics ships are part of the sailing branch's new requirement for so-called "Afloat Forward Staging Bases," essentially barges carrying boats, helicopters and special operations forces. The first one, the retrofitted USS Ponce, is currently in the Persian Gulf supporting minesweepers.

This is a gamble. Right as the Navy's lowering its shipbuilding sights, it's about to get a whole lot busier. The anticipated "rebalancing" to Asia and the western Pacific places the Navy at the center of U.S. defense strategy. Defense Secretary Leon Panetta and Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, are already questioning whether impending budget cuts render that strategy a non-starter. Even if they don't happen, it remains to be seen if the Navy can shoulder that greater burden with fewer ships.

All these projections are tentative, of course. The Navy's new plan is no more set in stone than the previous one, and could change as budgets and strategy do. And the year-on-year shifts mask two important truths: the Navy still expects to get bigger in the near future, if not as big as it anticipated. Even if it doesn't, it's still by far the largest and most powerful maritime force on the planet.