Cuban leader Fidel Castro has threatened to pull his country's boxing team out of the world championship in the US to prevent fighters defecting.
Lara (L) and Rigondeaux may be banned from competing for Cuba
Cuba would not sacrifice its honour for Olympic gold medals, Mr Castro wrote in the state-run Granma newspaper.
The championship is a qualifying event for the 2008 Beijing Olympics. In 2004, Cuba won the majority of its nine Olympic gold medals in the boxing ring.
Last month, two Cuban boxers abandoned their team at an event in Brazil.
Guillermo Rigondeaux and Erislandy Lara, both amateur world champions, were deported from Brazil to Cuba on Monday after their apparent attempt to defect during the Pan-American Games in Rio de Janeiro.
'Patriotism shall prevail'
Cuban sports officials were considering all options to prevent defections, Mr Castro said, including sending an alternative team to Chicago in October, or not sending any boxers at all.
"The morale and patriotism of [Cuba's] athletes shall prevail above all else," the 80-year-old leader wrote.
Sporting success is a matter of national pride in the communist country, says the BBC's Michael Voss in Havana.
Boxing is one of its specialities and it has produced a long line of Olympic champions.
But Cuban athletes have in the past used overseas sporting events to defect, often to lucrative professional contracts, our correspondent says.
'Point of no return'
In the most recent case, Rigondeaux, a double Olympic and amateur world bantamweight champion, and Lara, a world amateur welterweight champion, failed to show up for their fights in Rio despite being favourites to win gold.
Brazilian police detained them last week for overstaying their visas.
German sports company Arena said it had signed a contract with the boxers, who are forbidden in Cuba to switch from amateur to professional.
But an Arena spokesman told Brazilian media the boxers had later changed their minds about signing out of fear for their families' safety back in Cuba.
Mr Castro had initially said the two would be offered jobs in sport upon their return to Cuba. On Wednesday, he suggested they would not be allowed to compete for Cuba, saying they had reached a "point of no return" in Cuba's boxing team.
"The athlete who abandons his delegation is not unlike the soldier who abandons his fellow men in the midst of combat," he said.
The whereabouts of two other Cubans - handball player Rafael Dacosta and gym trainer Lazaro Lamelas - who also disappeared during the Pan-American Games are not known.