As one reason, Santorum cites "the emotions of men." The White House hopeful says there is the potential that men will not be focused on their combat mission but on what he calls a "natural instinct" to protect a woman.
Santorum also questions having women in combat roles because of what he says are "all sorts of physical issues" relating to the capabilities of men and women.
The Pentagon is putting into effect new rules that place women in the military closer to the front lines. The Pentagon still bans women from the most dangerous combat jobs.
Santorum made the comments Friday to CNN.