Top trade officials from the US and EU met on Monday to begin efforts to turn a much heralded deal to avert a trade war into a concrete long-term agreement.
After the meeting, EU trade commissioner Cecilia Malmstrom said she would meet US Trade Representative Robert Lighthizer again by the end of the month.
But neither side announced any immediate breakthrough.
"We discussed how to move forward and identify priorities on both sides," Malmstrom wrote on Twitter, "and how to achieve concrete results in the short to medium term."
Lighthizer's office called it a "constructive meeting".
The negotiators' cautious response to this first chance to "operationalise" plans for a limited trans-Atlantic trade pact came in stark contrast to the enthusiasm surrounding its birth.
In July, US President Donald Trump and European Commission head Jean-Claude Juncker pledged to hold off from further tit-for-tat tariffs and to work towards scrapping customs duties on all goods.
Both sides hailed the deal as a major breakthrough, but subsequent statements showed that disputes persist, especially over agriculture, which Washington insists will be a key part of any agreement.
"Lots of work remains this autumn, our services will be in close contact in the coming weeks," Malmstrom said, promising that technical teams will meet in October.
Under pressure from France, Europe refuses to allow farm goods be included in trade negotiations, creating a sticking point that Malmstrom and Lighthizer must get past.
"The idea is that the commission and the United States agree on a framework document, perhaps by the end of the year," a European source told AFP.
"Trump and Juncker have an agreement, but in reality, we didn't completely agree on the scope of the discussions," she added.
French Economy Minister Bruno Le Maire told AFP that agriculture remains a "red line" and that there is no question that it be included in the talks -- despite US insistence.
"The meeting between presidents Juncker and Trump allowed a return to dialogue, and that's positive," he said. "Beyond that, we have no illusions. We're a long way from a lasting solution."
The US delegation did not explicitly mention the farm dispute.
But its statement appeared to nod towards the agricultural issue by saying: "Specifically, we hope for an early harvest in the area of technical barriers to trade."
Officials had set very low expectations for the meeting, which is the first of several anticipated sit-downs to map out sectors in which common ground might be found.
- 'Bad as China' -
The summer's mending of fences was already fragile.
Last week, Trump harangued the EU and raised the spectre of slapping tariffs on Europe's auto industry.
Auto tariffs would be seen as a blow by Germany and would add to existing levies on steel and aluminium that Trump imposed on Europe in June. The EU imposed a raft of counter-duties in return.
Last month, Malmstrom said a trade deal could include scrapping transatlantic tariffs on autos, but Trump swiftly excluded the possibility, arguing that Europe was virtually closed to US cars.
"It's not good enough," Trump said, speaking of the Brussels offer.
Trump also worryingly compared the EU to China, which on Friday received a threat of tariffs on all goods exported to the United States.
"The European Union is almost as bad as China, just smaller," Trump told Bloomberg on August 31.
But the Europeans, led by jittery Germany, want the US at the negotiating table and seem ready to hand Trump small victories in exchange for a truce.
Since July, the EU commission has announced a series of commitments to the US, but observers note that these are largely done deals.
Most celebrated by the White House is a huge increase in European purchases of US soybeans that Trump says vindicates Washington's toughness and resolve against its partners.
EU officials, however, say the explosion in demand is purely a market phenomenon and a knock-on effect of Trump's trade war with China.