The gates in this verse refer to the city gates of Nineveh. If the city falls, the whole land falls. Nahum says that the gates are completely open to the enemy. He may be talking metaphorically, saying that Nineveh is going to fall easily, or it could be that the bars that are used to keep the gate closed have been used for fire because of the siege, which means the gates cannot be closed.1 Either way, Nahum is again taunting Nineveh with the reality that she will not withstand the invasion that is coming.
13 Behold, your troops are women in your midst. The gates of your land are wide open to your enemies; fire has devoured your bars.