A British nuclear submarine has joined the search for Malaysia Airlines Flight MH370 almost one month into the daunting hunt for the missing jet carrying 239 people.
HMS Tireless has already arrived in the southern Indian Ocean and brings its advanced underwater search capabilities to the mission, the U.K.'s Ministry of Defense said.
It will join up to eight planes and nine ships searching an area of around 86,000 square miles - roughly the size of Minnesota - some 1,000 miles west-north-west of Perth, Australia.
Australian Prime Minister Tony Abbott said Thursday that the search was the "the most difficult in human history," according to a Reuters report. He added Australia, which is coordinating the search, is "throwing everything we have at it."
Also on its way to the search area is an Australian navy ship fitted with a U.S. black box detector and an unmanned submarine.
Malaysia's Acting Transport Minister Hishammuddin Hussein said Wednesday he spoke on the telephone with Britain's Defense Minister Phillip Hammond who confirmed the submarine would be joining the search.
The U.K. Ministry of Defense said in a statement that the Trafalgar Class submarine arrived in the region Tuesday. "With her advanced underwater search capability, HMS Tireless will be able to contribute to the attempts to locate the missing plane," it said.
Reuters contributed to this report.