Pentagon spokesman John Kirby said on Monday the U.S. has sent a towed pinger locator, an autonomous underwater vehicle and trained personnel to Australia in case the equipment is needed to search for the black box of the missing Malaysia Airlines jetliner.

A towed pinger locator and a Bluefin-21 autonomous underwater vehicle were flown out of JFK Airport in New York to Perth, Australia earlier the day, and expected to arrive there on Tuesday, Kirby confirmed at the Pentagon press briefing.

"There will be a small number of people going along with them," he added. "I think there are two on the flight with the gear itself, and then another eight folks will be flying separately to Perth to prepare the equipment."

The towed pinger locator could be used to locate the missing airliner's black box, while the Bluefin-21 autonomous underwater vehicle has sophisticated sonars that could be used to locate wreckage, he said.

The underwater unmanned vehicle can dive to 14,700 feet, and if needed, the vehicle will operate off an Australian commercial ship, he said.

However, Kirby stressed that the equipment is being sent to Perth just in case "there be a need."

"We don't have a debris field that we can go look for specifically," Kirby said. "We don't have anything to indicate where the aircraft is, or even that it is down at the bottom of the ocean."

Asked if the U.S. Navy will step up search efforts in the region, Kirby said there is "no immediate changes on the horizon that I see from the U.S. Navy's perspective."

The U.S. side is currently "focused on fixed-wing aircraft" with one P-3 and one P-8 patrol aircraft and the equipment that Beijing sent there in case it is needed, he said.

"Search missions in general, particularly those at sea, they change over time based on the conditions and based on the information that investigators continue to accrue," Kirby said, "So, we'll see."

Earlier in the day, Malaysian Prime Minister Najib Razak announced the missing plane's crash at a press conference citing new analysis of satellite data from a British satellite provider and the British air accident investigation unit.

Asked if the Pentagon has known of this British side's analysis, Kirby said he doesn't know that "leaders here in the Pentagon were specifically aware of that."

U.S. State Department said on Monday it has no "independent corroboration" about the announced crash of the missing Malaysian jetliner in the southern Indian Ocean.

"I don't have any independent corroboration of that," the State Department spokeswoman Marie Harf told reporters at a regular news briefing,

"I have no reason to believe it's not true. I just don't have any update for you," Harf said, adding Washington was working "very closely" with the Malaysian government.

Najib said the missing Malaysia Airlines Flight MH370's last position was in the middle of the Indian Ocean, west of Perth, Australia.

The Boeing 777-200 aircraft, carrying 227 passengers and 12 crew members en route from Kuala Lumpur to Beijing, disappeared from radar in the early hours of March 8.