Canada and the United States are unlikely to strike a deal on a dispute over lumber exports by the time talks on renewing NAFTA start in mid-August, a source close to the matter said on Thursday.

U.S. Trade Representative Robert Lighthizer said earlier in the day he hoped the issue would be solved before the formal start of negotiations on the trilateral North American Free Trade Agreement.

“It’s hard to imagine a deal being done that soon,” said the source, who declined to be identified due to the sensitivity of the matter.

Washington last month imposed tariffs on Canadian softwood lumber exports, triggering the fifth formal bilateral dispute over timber in less than 40 years. The legal battles can take years to resolve.

Canadian Foreign Minister Chrystia Freeland told legislators late on Wednesday that “the United States, when it comes to softwood lumber, has made no offers that any Canadian would consider to be acceptable”.

Freeland, who has raised the matter with U.S. Commerce Secretary Wilbur Ross and other senior officials, added: “I do not feel that any of those conversations from the U.S. side have yielded a sufficiently good basis for a really meaningful negotiation to take place.”