By Phil Stewart and David Alexander
WASHINGTON, March 21 (Reuters) - The U.S. military's search for the missing Malaysian jetliner has cost $2.5 million so far, the Pentagon estimated on Friday, adding it has set aside about $4 million for the hunt so far, enough to cover operations through early April.
It was the first disclosure of costs for the U.S. ships and aircraft joining the search for Malaysia Airlines Flight MH-370, which went missing almost two weeks ago with 239 people aboard.
The United States initially dispatched the Navy's guided-missile destroyer USS Kidd, as well as the USS Pinckney, to comb the seas for any signs of wreckage. They have been withdrawn.
Two U.S. spy planes are now hunting for the jet, including an advanced P-8A Poseidon designed to spot submarines.
Pentagon spokesman Colonel Steve Warren acknowledged that some of the costs of the hunt would have been money spent regardless. He did not say whether the United States might seek any reimbursement from Malaysia.
"As of now, we've set aside $4 million to aid in the search. Based on our current expenditures, we expect these funds will last until sometime in the beginning of April," Warren said.
That is not a deadline, however. At the Pentagon on Thursday, spokesman Rear Admiral John Kirby said: "We're going to stay with this as long as the Malaysians need our help."
Earlier on Friday, Malaysian Defense Minister Hishammuddin Hussein said via Twitter he would speak to U.S. Defense Secretary Chuck Hagel about the need for "pinger locator hydrophones".
The Navy has a system called a "Towed Pinger Locator", an underwater listening device towed behind ships that is used to search for downed Navy and commercial aircraft at depths of up to 20,000 feet (6000 meters), according to the U.S. Navy's website.
The P-8 spy plane also carries sonobuoys that can be dropped into the sea and use sonar signals to search the waters below.
The Pentagon confirmed the call but did not immediately provide details on any requests.
The international team hunting Malaysia Airlines Flight MH370 in the remote southern Indian Ocean failed to turn up anything on Friday, and Australia's deputy prime minister said the suspected debris may have sunk.
International aircraft and ships have also renewed a search in the Andaman Sea between India and Thailand, going over areas that have already been exhaustively swept to find some clues.
Beyond dispatching the P-8A Poseidon, the U.S. Navy has also dispatched its P-3 spy plane. That aircraft was expected to shift its search toward the remote Cocos Islands from the Bay of Bengal, the Pentagon said.
"I don't have an exact timeline (for the shift in search area). I believe over the weekend," Warren said. (Reporting by Phil Stewart; Editing by Stephen Powell)