The U.S. military has spent $11.4 million in the search for missing Malaysia Airlines Flight 370, according to officials at the Pentagon.
That includes $3.6 million for underwater surveillance by a Navy submarine and $4,200 per flight hour for the P-8 Orions used to scour the southern Indian Ocean.
The Pentagon has previously said there are no plans to ask the Malaysian government for reimbursement.
So far, the high price comes with few concrete leads. A contingent of countries, which includes Malaysia, Australia and China, have failed to find any physical evidence of where Flight 370 crashed after disappearing March 8 from Kuala Lumpur en route to Beijing.
After several false leads, sonar technology appeared to pick up a frequency earlier this month consistent with a plane’s black box. The search field has been narrowed to about 1,000 miles northwest of Perth, Australia.
An unmanned submarine, the U.S. Navy-owned Bluefin 21, has finished sweeping about 80 percent of that 120-square-mile patch of water, Australian officials said Wednesday. Nothing of interest has been located, and officials expect to use more powerful sonar equipment once the Bluefin’s job is done.
Another clue — possible sheet metal with rivets seen washed ashore on Australia’s coast — does not appear to be from the plane’s wreckage, officials said.