What are the major issues that the U.S. government is facing in protecting its borders from illegal immigration and its citizens from domestic and foreign terrorist attacks?

The U.S. government has been facing a lot of issues in its fight against illegal immigration and foreign terrorist attacks. One of these issues has to do with the high cost of border security as the security increases as years go by. Provision of enough people to help border control is a requirement but it is also a costly cause that requires billions of dollars. Cost of removal of immigrants from the United States is another costly cause. The U.S. government has to account for these costs as well. The border fence is another thing to be taken into cost consideration.