Obama met with British Prime Minister Theresa May at the start of a G20 summit in China as Britain embarks on the long process of reinventing itself as an independent trading nation following the shock June EU referendum outcome.
Smiling for now Theresa May UK PM
He offered May reassurance that Britain's closest political, commercial and military ally would stand by her, but did not shrink away from his stance that Brexit was a mistake and that London would not be able to jump the queue to arrange a bilateral deal.
"It is absolutely true that I believed pre-Brexit vote, and continued to believe post-Brexit vote, that the world benefited enormously from the United Kingdom's participation in the EU," he said.
"First things first - the first task (for Britain) is going to be figuring out what Brexit means with respect to Europe, and our first task is making sure we get, first, TPP (Trans-Pacific Partnership) done and also that we move forward on the TTIP (Transatlantic Trade and Investment Partnership) negotiations in which we've invested a lot of time and effort."
TTIP is a stalled U.S.-EU trade deal, while TPP is Obama's signature Asian trade deal.
Australian Prime Minister Malcolm Turnbull[pictured below], meanwhile, said on Sunday his country and Britain were both very committed to having an early free trade agreement after Britain leaves the European Union.
"They've got to put in place free trade agreements and we are enthusiastic and supportive; we're providing Britain with as much assistance as we can at a technical level," Turnbull told reporters in Hangzhou.
The President Obama and Prime Minister May leaving after the press conference
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