The Navy cannot continue operating at the current worldwide tempo without putting at risk the expected lifetimes of its ships and aircraft, a top admiral warned yesterday.

Vice Adm. Terry Blake, the deputy chief of naval operations for capabilities and resources integration, said as of this week 133 of the Navy’s 283 ships are deployed–a rate of 47 percent that is not sustainable over the long run.

“We’ve got to figure out how to operate with less than that out there because if you continue to operate on a wartime footing, as that is, that is an unsustainable model if we’re going to be able to get our ships and aircraft to the end of their expected service lives,” Blake said at a breakfast sponsored by the Navy League. “We are burning up the ship lives and the aircraft lives.”

The demand from combatant commands for assets in their global areas of responsibility have not declined despite the end of the war in Iraq and the drawdown of forces in Afghanistan, Blake said at an event hosted by the Navy League.

“If we don’t have any more assets we’ve got to prioritize what we’ve got and parse them out appropriately,” he said. He added more wear on ships and aircraft could add up to higher maintenance cost over their lifetime.

Under the budget squeeze the Pentagon is facing, the Navy expects to have about the same number of ships in five years as it does now. In its five-year shipbuilding plan unveiled Feb. 13 alongside its fiscal 2013 spending request, the Navy proposed building 41 ships–57 fewer than originally planned.

The Navy set a goal several years ago to build and sustain a fleet of 313 ships, but that objective could be on hold because of diminishing budgets. The service is conducting a new force structure assessment in light of the Obama administration’s revised global strategy outlined in January that places heightened focus on the Asia-Pacific. Blake would not put a timeframe on the completion of the Navy’s fleet size assessment.

The new strategy that relies largely on sea and air capabilities has raised questions as to whether the Navy will be able to execute it without elevating annual ship construction.

“I’m concerned that budget cuts of this significance to our Navy and armed forces will increase our risk in this theater,” Rep. Howard “Buck” McKeon (R-Calif.), the chairman of the House Armed Services Committee, said during a Navy budget hearing Feb 16.

Adm. Robert Willard, chief of Pacific Command, told the Senate Armed Services Committee Tuesday that while the number of ships in the Navy’s fleet is important, it’s of greater significance to ensure forces are well positioned in key areas of the world such as the Asia-Pacific region.

“It’s more important with regard to how we bias those ships globally and whether or not the area of responsibility, that, as you suggest, is a vast maritime one in the Asia Pacific, is being adequately serviced,” he said when asked by Sen. Roger Wicker (R-Miss.) about the Navy falling short of the 313-ship goal.