Delta Air Lines is ending its three year codeshare agreement with the French railway system SNCF on December 1.
The troubled US carrier gave no firm reason other than that it was a strategic business decision and it wished to focus its efforts in France on its SkyTeam partner Air France.
The deal when it was signed in 2001 was one of the first of its kind of co-operation between a US transatlantic carrier and a European national rail network.
Under the agreement travellers on Delta from the US who were bound for Paris's CDG airport could travel on from there on the same seamless ticket to 12 French towns and cities.
It was also valid for travellers from those 12 locations to travel seamlessly on Delta to US destinations via CDG.