[1][2] Calero was responsible for managing the bank accounts into which money was deposited and then used to buy supplies and arms for the Contras.
In a bid to unify contra factions and win aid from the US Congress, he became a member of the United Nicaraguan Opposition (UNO) triumvirate with Alfonso Robelo and Arturo Cruz.
Calero controlled the FDN through his deputy, Aristides Sánchez, and the Contras' military commander, Enrique Bermúdez, an alliance so tight that it was dubbed the "Iron Triangle."
After the Sapoa ceasefire, Calero exploited discontent with Bermudez among the FDN's field commanders in an effort to push him out.
On July 26, 2011, he published his book, Cronicas de un Contra, which narrates his participation during the 1980s in Nicaragua.