Washington (CNN) -- Nine Air Force commanders lost their jobs in the wake of a cheating scandal involving systemic cheating on tests by officers in the U.S. nuclear missile program, officials from that military branch said Thursday.
The fired officers were in "leadership positions" at Malmstrom Air Force Base in Montana, Air Force Secretary Deborah Lee James said. Though not directly involved in cheating, "they failed to provide adequate oversight of their crew force," according to James.
In addition, Col. Robert Stanley -- head of the 341st Missile Wing and a 25-year veteran -- "relinquished command" and submitted his resignation Thursday morning, said Lt. Gen. Stephen Wilson, the commander of the Air Force's Global Strike Command.
"Leadership's focus on perfection led commanders to micromanage their people," said Wilson, pointing to pressure to get 100% scores on monthly proficiency exams when only 90% was necessary to pass. "... Leaders lost sight of the fact that execution in the field is more important than what happens in the classroom."
James said Thursday that 100 lower-level officers were at one point implicated in the ordeal -- having either been accused directly of cheating or having looked the other way. Nine of those have been cleared and will be allowed to return to duty, while others could face punishments ranging from letters of counseling to courts-martial on various charges.
These disciplinary measures are only part of the response, however. James and Wilson both referred to a number of changes to address this incident as well as far-reaching issues with morale, micromanagement and more among those in the Air Force's intercontinental ballistic missile program.
"The issues that we have before us today are tough, and they didn't come overnight," said James. "... While we have progress in certain areas in recent years, there is more work to be done."
Military investigators stumbled into the cheating scandal while looking into alleged drug activity involving airmen. Three of their targets in the drug probe happened to work as missile crew members at Malmstrom, which is how investigators got access to their cell phones -- and "found test material on them," according to Wilson.
Authorities previously said the cheating took place last August and September at the Montana base, with officers using texts and pictures to cheat on their proficiency exams.
But Wilson said Thursday that such behavior actually went well beyond that, having occurred as far back as November 2011 and as recently as November 2013.
The whole Malmstrom scheme centered on four individuals, three of whom were being investigated in the drug probe, according to Wilson.
"If we would have removed those, then this incident probably would never have happened," he added.
About 190 officers oversee the readiness of nuclear weapons systems at the Montana base, meaning the episode tainted a large percentage of that force in some way. James said she found worrisome not just that airmen cheated directly, but that no one -- whether or not they were directly involved -- spoke up.
The Air Force officials said investigators didn't find any indication of similar cheating on other bases tied to the missile program, though they pointed to common issues elsewhere when it comes to the program's management.
To that end, Wilson said he has a list of "400 action items" to possible address those issues. Some are simple, like grading the monthly proficiency on a simple pass/fail metric. Others are more complicated, though all have a common aim of ensuring the nuclear weapons program is run smartly and effectively by satisfied, capable military personnel with high integrity.
"Our nation demands and deserves the higher standards of accountability from the force entrusted with the most powerful weapon on the planet," Wilson said. "We are committed to living up to those standards."
CNN's Shirley Henry and Barbara Starr contributed to this report.