It's been obvious to anyone conversant with geopolitics and international affairs that the United States' non-existent southern border presents a major national security threat. From Roman times until today, a nation that has not controlled its borders has, in time, found itself overrun. To quote a famous movie character, in this world, there are walls, and those walls have to be guarded by men with guns.

We're not doing that very well (a case could be made that we're not doing it at all), and now, in the latest development, a group of GOP lawmakers are concerned about the number of Chinese nationals crossing into the United States illegally.

A group of Republican lawmakers is warning the Biden administration about a rise in Chinese nationals coming across the southern border, claiming it proves their "worst fears" about what they see as a weakening of enforcement under the administration.

The 20 lawmakers, led by Rep. Bob Good, R-Va., highlights "the dramatic rise in encounters at our nation’s borders with individuals on the Terrorist Screening Data Set (TSDS) and the unprecedented, otherwise unexplained rise in Chinese nationals – largely adult males – crossing illegally."

"These developments prove our worst fears: the weakening of our borders and willful lack of enforcement of immigration laws has encouraged America’s adversaries to exploit this national security vulnerability," they say.

Is it necessary to point out that American-Chinese relations aren't exactly at their best at the moment?

When discussing illegal immigration and the open sore that is our national border, it's common to talk about culture, about the wage-depressing effect of a sudden influx of cheap labor, of the criminals in the ranks of these pouring in. Those are all legitimate points — but so is the national security threat posed by this failure on the part of the Biden administration.

See Related: ICE Apprehends Rapist, Child Abuser, Other Dangerous Illegal Immigrants in Major Bust 

OUTRAGE: Sources Say Biden Administration Has Granted De Facto Amnesty to 350K Illegal Immigrants

If one was a nefarious actor who wanted to infiltrate a bunch of people into the United States, a bunch of people who arrive unidentified, unscreened, and largely unknown, this would be precisely how one would go about it — and under the Biden administration's non-existent border policies, this is also the perfect time to do it.

It's not just people from China, either.

Shortly after midnight on May 18, a Boeing 777 operated by the Libyan airline Ghadames Air took off from Benina International Airport in Benghazi, the largest city in eastern Libya and landed 14 hours later at an airport in Managua, the capital of Nicaragua. According to the Nicaraguan television channel 100% Noticias, 367 passengers of Indian nationality were on board. On May 23, the same aircraft made the same flight with 298 Indians. All intended to continue on to the US.

Earlier, on February 28 and March 14, two similar flights left the Libyan capital, Tripoli; no information about the passengers' nationalities has been disclosed. When contacted, neither the Nicaraguan Ministry of Foreign Affairs nor the country's airport authorities responded to Le Monde's inquiries about what appears to be the opening of a new route to the US border for undocumented immigrants.

Libya, we might point out, is likewise not friendly to the United States. Neither is Daniel Ortega's Nicaragua. India is a U.S. ally, but how many people from other parts of the Middle East are on these flights? Are there any from, say, Syria — or Iran? There is, as noted, no information forthcoming from these flights.

This is a serious matter of national security. As I have been pointing out, and I think I have already worn out at least two keyboards doing so, we have no idea who many of these people are, where they are going, or what they intend to do when they get there. We do know that many of them have come from regions not friendly to the United States — and sooner or later, all this is going to catch up with us.

My Townhall colleague and fellow U.S. Army veteran Kurt Schlichter has penned a chilling work on how all this may play out. It's not a read for the faint-hearted. But if we are to prevent such an event, controlling our borders and deporting the people who are here illegally would be a good start.

One of the reasons for the fall of Rome is proposed to be their failure to control their borders. As proposed by Peter Heather in his book "The Fall of the Roman Empire," Rome had for hundreds of years welcomed immigrants but had insisted they assimilate; but that final wave, out of Germania, retained their Germanic cultural and ethnic identity, established themselves in enclaves within the Empire, and eventually built armies of their own that the weakened Rome, much of whose military was away from Rome fighting in Persia, was not able to withstand. Sound familiar?

History, as the saying goes, may not repeat, but it frequently rhymes.