With clear threats to our national security from current political instability in Syria, Afghanistan, and Venezuela, to rising Chinese influence in the developing world, few decisions are as consequential as the selection of the next secretary of defense.
Since Gen. James Mattis resigned in December, the top position at the Pentagon has remained vacant. While it is imperative to find and confirm a replacement soon, both President Trump and Congress must carefully consider who they select as the next leader of the Pentagon.
Our country needs a disciplined, resourceful, and forward-thinking leader who understands the threats we face and will bring together all the tools in America’s arsenal to address them. This requires the coordination of efforts between the military, the diplomatic corps, and development personnel. I often saw this type of leadership in the military commanders I reported to and worked alongside during my 23-year career in the Marines.
In turn, their example helped shaped my own leadership approach. During my tenure as mayor of Indianapolis, I stressed collaboration on multiple fronts — departments, city-county council, community groups, constituents — and strove to reconcile differing perspectives, especially when seeking creative, effective solutions to complex problems. I listened well.
Much like a mayor, the secretary of defense should rely on collaboration to achieve goals and to minimize risk: collaboration with allies, the Joint Chiefs, the service chiefs, the combatant commanders, along with our civilian leadership at the State Department and USAID. These partnerships should remain a cornerstone of our national security strategy.
Our military has always understood that keeping our country safe is not the job of the military alone. Former Defense Secretary Robert Gates knew this when he formed close ties with Secretary of State Condoleezza Rice. They jointly advocated for defense alongside “our civilian instruments of power,” making it clear that development and diplomacy are crucial to keeping our nation safe while strengthening U.S. global leadership. Gates elaborated on this stance when he said, “Development is a lot cheaper than sending soldiers” and therefore must be incorporated into America’s national security strategy.
Mattis also worked hand-in-hand with his counterpart at the State Department — first Rex Tillerson, then Mike Pompeo — to bolster the United States’ strategy. For him, diplomacy was the first line of defense, given its power to prevent conflict and forge partnerships with allies. Before becoming the secretary of defense, Mattis famously summed up his views in 2013 when he told Congress, “If you don’t fund the State Department fully, then I need to buy more ammunition ultimately.”
My experience has been that our regional combatant commanders and strategic level military leaders have a history of understanding the importance of such collaboration. Although I was on the ground during the Persian Gulf War in 1990-1991, I understood the importance of the diplomatic effort to the ultimate outcome of that conflict.
Our American diplomats worked alongside our military leaders to create a highly effective coalition, while also de-escalating mounting tensions between Israel and the Arab states, even orchestrating the first face-to-face talks between those countries in decades. These superior efforts allowed the troops on the ground to focus on their critical mission and produce a military victory in almost textbook fashion.
The understanding of this need for collaboration with our diplomats and development personnel is still present today. Very recently, General Thomas Waldhauser, Commander of U.S. Africa Command, testified before the House Armed Services Committee, “Our activities directly complement Department of State and USAID efforts to reduce the spread of harmful ideologies, strengthen governments who protect their citizens, and foster security and economic successes.”
Also, in Afghanistan, American officials have reached a preliminary peace agreement with the Taliban to withdraw troops after nearly two decades in that country. While only time will tell if this effort proves successful, the power of diplomacy combined with our military prowess has proven to be of great value throughout the history of our country.
Whoever is nominated as the next secretary of defense, it is important to recognize that collaboration is key to a robust national security strategy. By cultivating relationships with key partners at the State Department and other organizations, and matching our military strength with our civilian tools of diplomacy and development, we can keep our nation safe while advancing American leadership around the world.
Greg Ballard is a retired Lt. Col. in the U.S. Marine Corps and former mayor of Indianapolis. He is the author of the new book, Less Oil or More Caskets.

