- Video report by ITV News Political Correspondent Paul Brand
David Davis admitted that talks with Europe regarding the UK's Brexit divorce bill were "getting a bit tense".
Speaking after a speech in Washington DC, the Brexit Secretary said the third round of talks had seen "tough" discussions regarding the size of the UK's exit bill.
He said he had ruled nothing in or out regarding whether Britain would pay part of its exit bill during a transition period.
He said: "What's been going on is that we have got to the point today where there has been some pressure over the last couple of days, pressure over the question of whether we pay a divorce bill, a separation bill, and if so what it is.
"What we've been doing, as you do when someone provides you with a large bill, is go through it line-by-line. And we've got very good lawyers."
He continued: "We are in a difficult and tough and complication negotiation. I have said from the beginning it will be turbulent.
"What we're having at the moment is the first ripple and there will be many more ripples along the way."
His comments come after Liam Fox's accused the EU of "blackmailing" the UK over the final bill.
Speaking about the European Union's insistence on agreeing a bill before moving on to trade talks, the International Trade Secretary told ITV News: "We can't be blackmailed into paying a price on the first part [the divorce bill]."
Mr Davis confirmed the there would be no US trade while Britain remains in the European Union or transitioning out of it.
This would mean no deal with USA until 2021 at the earliest.