The wall doesn't need to be physical. It works as obstacles to slow down movement of the enemy. For example, Google has built up its own wall by making practic

The wall doesn't need to be physical. It works as obstacles to slow down movement of the enemy. For example, Google has built up its own wall by making practical extremely large computing platform. That's a big wall for them to deter competitors. Apple focus on user experience and that is a big wall for them to fend off copycats. If U.S. has to build a big wall. The wall has to be something that make U.S. an aspiration for those enemies of our enemies, such as rebel students in Tehran or Beijing.