[Political Junkie Too]

The Posse Comitatus Act prohibits the use of the Army on US soil for law enforcement purposes. It does not prohibit the use of the military for Constitutional purposes, such as the Article IV Section 4 protection of states against invasion or domestic violence.

Article IV Section 4

The United States shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened) against domestic violence.

The President could use the Army to secure the southern border from an advancing caravan of foreigners intent on illegally entering the country. This would not be "law enforcement," as these are people not already in the country, and who are determined to bypass border security and lawful entry procedures.

Should this caravan succeed in breaking border control and massively enter the country as a mob, the military can be used to protect against the domestic violence that will ensue.

If there are any post-mid-term election riots, or if the advancing caravan breaks through the border and incites riot, the President could use the Army to quell the riots because Congress would be in recess, or he can use his Article II Section 3 power to convene Congress immediately into an "extraordinary occasions" session to have Congress formally appeal to the President to deploy the military to quell domestic riots.

-PJ

[Yo-Yo]

The minute the mob deploys tanks and small arms, the Army will deal with them.

If you bothered to read the article I linked to, you would have seen this:

The Posse Comitatus Act and subsequent legislation specifically prohibit the use of the Army, Air Force, Navy and Marines to enforce the domestic laws of the United States except when expressly authorized by the Constitution or Congress. Since it enforces maritime safety, environmental and trade laws, the Coast Guard is exempt from the Posse Comitatus Act.

While Posse Comitatus does not specifically apply to the actions of the National Guard, National Guard regulations stipulate that its troops, unless authorized by Congress, are not to take part in typical law enforcement actions including arrests, searches of suspects or the public, or evidence handling.

Arresting and deporting illegal aliens is a domestic law enforcement activity.

If POTUS declares Martial Law, then the Army can perform domestic peace-keeping functions. But Martial Law has not been declared, so Posse Comitatus still applies.