Malaysia's Defense Minister Hishammuddin Hussein designated two search corridors Tuesday, with Australia and Indonesia taking point on the southern section and China and Kazakhstan taking areas closer to their respective countries.
A U.S. official, speaking on condition of anonymity, told CNN it's likely the plane is in the southern corridor.
"This is an area out of normal shipping lanes, out of any commercial flight patterns, with few fishing boats and there are no islands," said the official, who warned the search could take "weeks and not days."
The Boeing 777-200 disappeared March 8 on a flight from Kuala Lumpur, the capital of Malaysia, to Beijing, China, with 239 people on aboard.
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