As I said in the post only by turning humans into retards can zombies be a threat. There is no logic in zombies defeating a modern army.
Its a possibility if you account for widespread panic and total dissolution of social structures. Zombies can't defeat human race, but they can defeat human civilization.
I dont agree, while there would be a widespread panic, dissolution of social structures and the heavy casualties from initial shocking event of suddenly all dead people coming to life and trying to feast on the living. The moment army kicks in and cleans the place everything would go back to normal after some time. After all things like widespread panic and dissolution of social structures is common during any major world crisis either natural or man made, but humanity always bounces back.