PARIS — Two of the three largest commercial satellite fleet operators on June 12 said they would do what it takes to assure that a third viable rocket remains in the business to compete with SpaceX and Arianespace.

Karim Michel Sabbagh, chief executive of Luxembourg-based SES, and Michel de Rosen, chief executive of Paris-based Eutelsat, agreed that a duopoly between Arianespace and SpaceX was not viable.

“We will go the whole nine yards ­— the full distance — to make it work,” Sabbagh said of the effort to add a third launcher into the regular commercial rotation.

Eutelsat’s de Rosen said a duopoly would leave the industry exposed if, as happens on occasion, one of the two rocket suppliers suffered a failure that grounded its vehicle for several months.

SES and Eutelsat in the past have demonstrated their willingness to use a relatively untested rocket in the longer-term interests of sufficient rocket availability. Eutelsat made overtures to the Chinese, and SES was the first commercial fleet operator to use the Russian Proton and the SpaceX Falcon 9.

The options currently available to them appear limited. Both said they are counting on the Russian government to commit the necessary resources so that Proton, which has suffered four failures in four years, is returned to its previous reliability level.

In a panel discussion at the Paris Air Forum here, organized by La Tribune, a French financial newspaper, Sabbagh and de Rosen closed the door on any regular use of the Chinese Long March vehicle as long as U.S. technology-export rules prevent U.S.-built satellite parts from being exported to China.

Both praised the Chinese Long March rocket’s reliability but said the U.S. technology export policy is too high a hurdle to bring China back into the market.

The two chief executives expressed the hope that, ultimately, regulatory barriers to using Chinese rockets will be removed. Until then, they said they stand ready to support Russia’s Proton and its successor, Angara, as the necessary third commercial vehicle.

De Rosen took issue with statements repeatedly made by French politicians and others that attribute SpaceX’s success to U.S. taxpayer largesse.

“This is exaggerated,” de Rosen said. “First of all, SpaceX’s support from NASA is in the form of contracts, not subsidies. And even these total less than what the European taxpayer is paying to develop the Ariane 6 rocket. There is a tendency in Europe to look at a non-European’s success and conclude, ‘He’s cheating.’ Yes, [SpaceX Chief Executive] Elon Musk has been aided, but he has done a lot.”

European governments in December agreed to spend about 8 billion euros ($9 billion) over 10 years to continue supporting the Ariane 5 heavy-lift rocket and to develop the new Ariane 6 vehicle.

Francois Auque, chief executive of Airbus’s space division ­— which is prime contractor for the Ariane 5 and Ariane 6 — said his company has never underestimated SpaceX especially after sending its two top technical officers to Hawthorne, California, to spend a week at the SpaceX facility.

“They came back and said, ‘They’re going to make it work,’” Auque said. “Musk later asked us to invest in SpaceX, but I thought this would have been politically incorrect. But I did purchase a Falcon 1 from him because that did not compete with Ariane.”

The Airbus contract has since been transformed into a Falcon 9 contract.