President Trump at the White House on Wednesday. (Joshua Roberts/Reuters)
Opinion writer

The Post reports:

President Trump said Wednesday that he would deploy as many as 15,000 military personnel to the border with Mexico in response to caravans of Central American migrants making their way northward, doubling the figure Pentagon officials have announced would be operating there.

“We’ll go up to anywhere between 10 and 15,000 military personnel on top of Border Control, ICE and everybody else at the border,” Trump said in remarks to reporters before departing Washington for a campaign rally in Florida. “Nobody’s coming in. We’re not allowing people to come in.”

Trump says he wants a “wall of people,” which sounds like something that would have been in vogue during the Middle Ages. We shouldn’t be even sending 5,000 troops. (“Deploying forces domestically in relation to such a politically charged issues risks eroding the public support that the armed forces enjoy with the American public.”)

Remember, we are talking about a shrinking caravan of mostly destitute women and children who are hundreds and hundreds of miles from our southern border. By comparison, the Mariel boatlift in 1980 brought nearly 125,000 Cubans to Florida — many of whom became stalwart Republicans. (Granted, that was during a time when Republicans opposed ruthless dictators and welcomed those struggling for freedom.)

Then let’s remember another surge in refugees:

Following the final collapse of South Vietnam in 1975, the U.S. evacuated some 130,000 Indochinese — Vietnamese, Cambodians and Laotians — fleeing the new Communist government. Americans were deeply divided on whether these refugees should be allowed to live in the United States: In a May 1975 Harris poll, for example, 37% were in favor, 49% opposed, and 14% weren’t sure. Nonetheless, the refugees were allowed to stay.

Later in the decade, hundreds of thousands of people living in Vietnam (including many ethnic Chinese) began leaving the country in overcrowded boats. At the same time, thousands of Cambodians and Laotians were escaping their countries over land. In response to the humanitarian crisis, President Jimmy Carter in June 1979 doubled the number of Indochinese refugees the U.S. had previously agreed to accept, to 14,000 a month. The move was not popular: In a CBS News/New York Times poll the following month, 62% disapproved of Carter’s action. But between 1980 and 1990, according to federal immigration data compiled by Pew Research Center, nearly 590,000 refugees from Vietnam, Cambodia and Laos were admitted into the U.S.

By 2017, more than 1.3 million Vietnamese lived in the United States. Now, people whom Trump and his ilk surely would have wanted to keep out “have higher incomes compared to the total foreign- and native-born populations. In 2017, households headed by a Vietnamese immigrant had a median income of approximately $63,200, compared to $56,700 and $60,800 for all immigrant and U.S.-born households, respectively.” It was a good thing we didn’t send a small army to keep out people fleeing communism who would become productive, loyal Americans.

Trump’s war against a nonexistent threat is so preposterous, and is such an obvious misuse of taxpayer dollars and an abuse of the military, that one wonders whether Trump’s anti-immigrant hysteria has reached the point of diminishing returns. The higher the already ludicrous number of deployed troops becomes, the more apparent his desperation becomes and the more people outside his core of xenophobic fans might conclude that we really do need Democrats in majorities in the House and Senate to head off this lunacy.

Trump’s insistence on demagoguing the issue — which was the impetus for the mail bomber and set off a mass shooting at a Pittsburgh synagogue — underscores the degree to which his party has become an irrational nativist movement. Rule of law (the old excuse for opposing “amnesty” for those here illegally)? Meh. An executive order will rewrite the Constitution to strip those born in this country of their U.S. citizenship. Market economics? Nah. It’s a Malthusian world in which each new person snatches resources and jobs from those already here.

If you want to know why the Republican Party has repulsed so many former adherents, you need look no further than its xenophobic delusions which waste money, abuse the military, incite racism and violence, work to our economic disadvantage and violate our deepest held values.