At the center of President Obama's strategy for dealing with the Islamic State is an empty space. It's supposed be filled by a 'Sunni ground force,' but after more than a year of effort, it's still not there. Unless this gap is filled, Obama's plan won't work.

We are aware only of the empty space in the forest, which only yesterday was filled with trees.

Our life is full of empty space.

An optimist is a driver who thinks that empty space at the curb won't have a hydrant beside it.

Nothing exists except atoms and empty space; everything else is opinion.

Empty political space will be filled by extremists unless the United States and its allies build strong local forces that can suppress terrorist groups and warlords both. When the U.S. creates such local forces, it must be persistent. If it withdraws from these efforts, as America did in Iraq in 2011, it invites mayhem.