There it is, in plain language, in Article IV of the United States Constitution:

“The United States shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion…”

Our federal government has not just a moral but also a legal obligation to protect the states — and, by extension, the American people — from foreign incursions. Yet today, among our progressive brethren, we are told instead that the government has an obligation to protect the impoverished of the world from the “heartlessness” of Republicans.

Enter the caravan. From out of nowhere (or more precisely, Honduras) a so-called caravan of impoverished Central Americans has been slowly working its way toward the southern border of the United States with the announced intention of seeking mass asylum in order to replace the hazards and hardships of their own countries with the blessings of liberty that we enjoy in the United States.

President Trump says that won’t happen. I say thank God for President Trump. For me, this caravan is an existential threat to the sovereignty of the United States. It is different in kind from the terror attacks of 9/11, but like them, it is an attack on our country and our principles. And as with all such attacks, it is crucial how we respond.

Although I was still a liberal Democrat at the time of 9/11 and had voted for Al Gore, I was so glad he wasn’t president when Islamic terrorists killed nearly 3,000 people on American soil that day. Would he have responded appropriately to the threat represented by Islamic fundamentalism? I didn’t think so. George W. Bush was the man of destiny who vowed to protect our country — and to do whatever was necessary to do so. He made mistakes, but any Democrat would have made a more critical mistake — to seek the approval of the world instead of the death of the terrorists.

Now, 17 years later, can you imagine if Hillary “Merkel” Clinton were president while 10,000 or more people (mostly young, able-bodied men) marched toward our southern border with the intention of breaking our laws and invading our peace? There is no way Clinton could or would stop the caravan, what with all the reporters saying how desperate and helpless and worthy the 10,000-person army is. And once she let the first 10,000 across the border, what would happen then? How long would it take for the next caravan to start up?

Has anyone ever heard of Europe? If you can’t learn from history that’s less than a decade old, then you are either obstinately stupid or just being misled by people with an agenda. Not even any other Republican president could reliably be counted on to do what is necessary to protect our sovereignty and our borders, let alone a Democrat. It’s Trump on the barricades, and Trump only. In this case, Bush with his globalist instincts would have been just as incompetent in responding to the caravan as Clinton. But Trump, with his damn-the-torpedoes approach, is the perfect person to protect our borders.

"They're not coming in. We're going to do whatever we have to; they're not coming in," Trump declared two weeks ago in the Oval Office.

It remains to be seen just what Trump will do, but he has drawn a line in the sand. So far, he has threatened to cut off foreign aid to Honduras, Guatemala and El Salvador and possibly Mexico in order to apply pressure to them to take action. He has also threatened to arrest and deport anyone entering the country illegally, but that is problematic thanks to the lenient courts that have granted rights to anyone who sets foot in the United States.

Trump knows this, which is why has also raised the stakes by threatening to engage the border crossers with the military. On Oct. 18, the day the president visited heartland Montana, he tweeted the following:

....In addition to stopping all payments to these countries, which seem to have almost no control over their population, I must, in the strongest of terms, ask Mexico to stop this onslaught - and if unable to do so I will call up the U.S. Military and CLOSE OUR SOUTHERN BORDER!.. — Donald J. Trump (@realDonaldTrump) October 18, 2018

It is possible Trump will even order troops into Mexico for the first time in over 100 years. If so, it won’t be for the purpose of conquest, but for the purpose of defense. That, after all, is one of the reasons the Founding Fathers established our constitutional government in the first place: “to provide for the common defense.”

Trump recognizes that if the border falls, the Constitution will not be far behind. We do not have the capacity to provide safe haven to every poor person in the world, but we can (for now at least) protect our own citizens and our own heritage. Again quoting the preamble, the Constitution was established to “secure the blessings of liberty to ourselves and our posterity,” not for the entire world.

You can’t secure the blessings of liberty unless you secure the border. Trump knows that. Now let’s hope he acts on it.