A multi-billion dollar submarine deal between long-standing allies - Australia, the UK and the US - has come under the spotlight after the Trump administration said it was reviewing how the deal fits in with its heavily-touted "America First" agenda.

The 2021 pact, meant to help counter China’s ambitions in the Asia Pacific, will be examined to ensure that it meets “America First criteria,” a U.S. official said.

Australia’s defense minister has dismissed concerns that a deal between the U.S., Australia and Britain to provide his country with nuclear-powered submarines could be in jeopardy, following a report that the Pentagon had ordered a review.