Froman also challenged the idea put forward by pro-Brexit politicians that the UK can immediately start discussing deals with other parts of the world. "The UK first and foremost needs to focus on how to define its future relationship with the EU and that will be its overwhelming preoccupation and it’s really impossible for anybody else to negotiate a free trade agreement with the UK until you know what is its competence," Froman argued.
During the referendum campaign, Brexit supporters including now-Foreign Secretary Boris Johnson said the UK outside the EU would be free to quickly negotiate its own trade deals with the rest of the world. Proponents of Brexit decried Obama’s comments as an attempt to intervene in the matter, using scare tactics to pressure voters into choosing to remain in the EU.
Now, Obama’s warning is "in reality the case," Froman said, adding that the UK government needs to concentrate on shaping its future trade relationship with the EU.
"Is it in a customs union with the European Union? Does it have control over its tariffs? Does it have control over its regulations?" Froman asked, adding that "those are still issues that are to be worked out between London and the other European capitals."
The priority for U.S. trade negotiators is the U.S.-EU Transatlantic Trade and Investment Partnership (TTIP) pact, Froman said. The UK would have been part of TTIP had it not voted to leave the EU.