The term "crisis" is chronically overused by politicians, but the numbers behind the debate over the “border crisis” speak for themselves. Between 16 and 29 million people are now living in the United States illegally, costing American taxpayers more than $100 billion a year.

Sixty thousand more are now illegally crossing the southern border each month, an 86 percent increase over last year.

In 2017, illegal immigrants were convicted of murdering 1,800 Americans and violently assaulting 48,000 more. Not one of these crimes should have occurred because not one of these criminals should have been in the country to begin with.

Finally, heroin kills 300 Americans every week, and 90 percent of it comes into the U.S. through the southern border.

The “caravan” that President Trump stopped in Tijuana attacked border patrol officers on New Year’s Day, and a much larger force is now on its way with the clear intention to cross the border illegally.

Trump might be a blunt force in American politics, but his insistence on confronting this issue has brought us to a turning point in American history. It has become a pivotal test of will, but ultimately not a test between the president and Congress or between Republicans and Democrats. It is a test of whether the American people can still summon the resolve to enforce their laws, secure their borders, protect their communities, and defend their sovereignty.

The congressional Democrats who oppose the president’s proposal insist that they support border security but then argue that a wall is a costly and ineffective way to stop illegal immigration. It is hard to take either claim seriously.

The Democrats have long advocated for providing a wide range of services for illegal immigrants, ranging from healthcare and legal counsel to education and housing, all at taxpayer expense. It is hard to argue convincingly that they want to discourage illegal immigration while simultaneously rewarding those who illegally immigrate.

Many Democratic officials have gone so far as to advocate abolishing the agencies that defend our borders. The Democrats long ago ceased to call illegal immigration what it is — illegal. They have enacted sanctuary laws that protect dangerous criminal illegal immigrants from deportation; opposed mandatory employment verification, to hold employers accountable for hiring illegal immigrants; supported enfranchising illegals; and opposed entry/exit tracking of foreign nationals entering our country.

Walls have been used for thousands of years to impede unauthorized entry, and for one reason: They work. And they still work. When Israel built a 144-mile wall to protect its southern border with Egypt, illegal immigration fell 97 percent. The $5.7 billion that Trump has requested to build a wall first authorized in 1996 is a fraction of the cost incurred by American citizens every year to support the illegal population in this country.

The wall doesn’t address the whole problem. It doesn’t address bogus asylum claims, hi-tech evaders, and the nearly half of illegal immigrants who arrive on visas that they violate. But a wall would be a tremendous force multiplier for border enforcement agencies, allowing them to implement vigorous tracking of visa overstays, enforce existing employment laws, stop drugs entering through legal ports of entry, and apprehend and deport criminal illegal immigrants.

The impasse cannot go on much longer, and the president cannot unilaterally appropriate funds for the wall. But in 1976, Congress authorized the president to reprogram already appropriated but unobligated military construction funds for the defense of the nation. And what is more central to national defense than the integrity of our borders?

Ironically, this approach has encountered Republican opposition. Some have argued that the money to secure our southern border would necessarily come from other Defense Department projects. It’s an odd logic that argues the defense of the Iraqi border is more important than the defense of our own border.

Others have worried that a presidential order would provoke a protracted legal challenge. But isn’t that true of any course the president could take? Others question the law’s constitutionality. The courts must settle that question, but while the law is on the books, the president clearly has the authority and obligation to use it.

If our immigration laws are not enforced, then our borders become meaningless, transforming America from a sovereign nation to a vast international territory between Canada and Mexico — both of which, by the way, have borders and immigration laws that they enforce.

History warns us that countries that either cannot or will not defend their borders simply aren’t around very long.

Tom McClintock, a Republican, represents California's 4th Congressional District.