"We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America."

In sort, defend our country and citizenry from barbaric invasion.  Mexico uses its army to defend illegal activities on the border, and fails to help enforce our immigration.

Our "POTUS" is without precedent in terms of not understanding that unless you defend a country, you don't have a country.