The EU must see movement from the U.K. in Brexit talks within two weeks in order to give a verdict of "sufficient progress" at the European Council summit in December, the bloc's chief negotiator Michel Barnier said Friday.

Speaking at a press conference concluding the truncated sixth round of formal Brexit talks in Brussels, Barnier was asked if he would need “clarifications or concessions” from Britain in the next fortnight in order for EU leaders to give the green light to move on to a transition period and the U.K.'s future relationship with the bloc.

Barnier responded simply: "My answer is yes."

Without specifying whether he was referring to the U.K.’s financial obligations, the status of EU citizens in the U.K. or the question of the Northern Irish border — or indeed, all three — Barnier managed with one word to put British feet to the fire.

David Davis, the U.K. Brexit secretary, did not respond or comment directly on the two-week deadline, though he seemed to smirk at Barnier’s response to the question.

“Continuous talks is the territory we’re getting into even if it’s not being labeled as that,” — U.K. official

He put the onus on Brussels to give some ground: “We need to see flexibility, imagination and willingness to make progress on both sides if these negotiations are to succeed."

Continuous talks

On one of these measures — flexibility — the Brits think they have finally won the argument.

London has been pushing for months to break the rigid structure of the formal Brussels talks and enter “continuous” negotiation. This is now where the talks are, Britain's negotiators believe. There is no formal round scheduled within the two weeks Barnier set out, so something will have to give in the ongoing, informal and regular contact between the two sides’ "coordinators," Olly Robbins and Sabine Weyand.

“Continuous talks is the territory we’re getting into even if it’s not being labeled as that,” said one U.K. official.

British negotiators now concede a breakthrough can only be achieved through political bargaining. If it was just a question of finding a technical definition of the U.K.’s financial obligations, for instance, the matter could have been settled weeks ago, one individual familiar with the U.K. position said.

Without being explicit, Davis conceded this point. “This is now about moving into the political discussions,” he said, “that will enable both of us to move forward together.”

Barnier noted that much of what happens during these set-piece negotiating rounds in Brussels depends on “technical experts … working with each other between the rounds.”

Technicalities and politics

On the key issue of the money, Davis said that the two sides had made “clear progress in building a common technical understanding on every item.”

For the EU, the big-ticket items, as set out in their negotiating documents as far back as May, are the reste à liquider — the sums still unpaid from the U.K.’s 12-13 percent share of the various EU spending commitments such as regional and overseas aid, estimated at around €30 billion — and contributions to the pensions of EU staff, thought to be roughly €8.75 billion.

Barnier gave a clue to how far the EU wants the Brits to go on this when he met British MPs earlier this week. For sufficient progress, he wants “principles and commitments to principles on the basis of which a final number can be calculated,” according to the Conservative MP and House of Commons Brexit committee member Jeremy Lefroy, who was present.

The sixth formal round of negotiations — really just a day and a bit of talks — ended on Friday with no substantial advancement.

That means Theresa May will have to move on one or both of those big-ticket items to get to where she wants to be by December.

Whether she can corral her unruly Cabinet into backing a major political decision on money will be the difference between a great leap forward and further stalemate.

Talks truncated

The sixth formal round of negotiations — really just a day and a bit of talks — ended on Friday with no substantial advancement, the chief negotiators said.

The talks, landing between the October and December European Council summits, had been an opportunity for “deepening our discussions, clarification and technical work,” said Barnier. The Brits, for their part, are not even referring to what happened this week as the sixth round of negotiations. In their eyes, talks are now continuous.

Barnier described serious outstanding differences on all three key divorce issues being discussed in Phase 1: citizens’ rights, the Northern Irish border and the financial settlement.

On citizens’ rights, he noted three key areas of continuing disagreement: family reunification, the exporting of social security benefits and the role of the European Court of Justice (ECJ).

And on Northern Ireland, Davis repeated the U.K.’s commitment to avoid "physical infrastructure" at the border between Ireland and Northern Ireland, but there was no clearer indication of how that would be achieved in conjunction with the U.K. leaving the EU’s customs union and single market.