With the U.S. military engaged in what experts consider a state of “persistent conflict,” the long-term stability and structure of the armed forces has become a topic of intense debate. While some see a need to keep an eye on conventional threats, others have pushed more radical ideas—like retooling the military to specialize on stabilization and training of foreign security forces.

Lt. Col. John Nagl and Lt. Col. Paul Yingling are among those advocating change. Both men have served with distinction in Iraq, and both currently command an army battalion. But they’ve also gone somewhere most uniformed officers seldom tread: They’ve taken their gripes with army doctrine public. In this podcast interview with CFR.org, Nagl argues the U.S. military must shift from a traditional combat force to one focused on advisory and stability missions. Yingling says a greater burden for war fighting and reconstruction must be carried by others branches of the U.S. government.

Their observations, which have won both supporters and detractors, were first raised in their professional writings. Nagl, who recently announced his retirement from the army (WashPost), explored lessons from past counterinsurgencies in his acclaimed 2002 book, Learning to Eat Soup with a Knife: Counterinsurgency Lessons from Malaya and Vietnam. Yingling made waves in May 2007 when he directly challenged the army’s officer corps with a scathing article blaming the failings in Iraq, like Vietnam, on the shortsightedness of a generation of generals.