Santos booted his defense minister, named a new armed forces commander and appointed new heads of the army, air force and navy, El Espectador reported Wednesday.
"I am sure that this will be a top team that will be next to the minister and at the head of the armed forces, giving a peace of mind to the country," Santos said.
The Colombian president said the military reform is the country's final blow to left-wing rebel groups that have been waging war in Colombia for nearly half a century.
The Revolutionary Armed Forces of Colombia, or FARC, is responsible for executing dozens in recent deadly hit-and-run attacks on government patrol units. The organization is Colombia's largest and oldest terrorist group.
Santos swore in Juan Carlos Pinzon as defense minister, appointed Adm. Roberto Garcia Marquez as navy commander and Gen. Tito Saul Pinilla as air force commander.