Early in World War II, my friend’s father put on his Civil Defense helmet and scanned the Coney Island beach for the arrival of German saboteurs. Maybe because he was so alert, Nazis never landed near the roller coaster, but on the West Coast similar no-shows nevertheless produced a panic. Soon enough, Japanese-Americans were incarcerated in detention camps.

I cite this history to assure you that Trump’s anti-immigrant snit has a precedent. We have been this stupid before. But never for less reason.

After all, the men who watched Brooklyn’s night sky knew the United States was at war. Japan had bombed Pearl Harbor and at least eight Nazis got to the East Coast, where two chose to surrender, the others were captured and all but the first two were executed. The panic was not totally without cause.

If there was panic this time, the cause was not terrorism, but Trump’s klutzy efforts to deal with it. Trump has arbitrarily barred residents of seven mostly Muslim countries from entering the United States. To cite just one of those countries — Yemen — no one can name a Yemenite who has carried out a terrorist attack here. But to cite another mostly Muslim country, Saudi Arabia, a child can tell you that it is where 15 of the 19 9/11 terrorists came from. Yet, Saudi Arabia is not on the list. It happens to be where Trump has business interests.

The Cato Institute, a libertarian think tank, looked into the matter of terrorist threats and came up with risk figures that seem taken from an astrology textbook: a 1 in 3.64 billion chance of an American citizen being killed by a refugee-turned-terrorist. David Miliband, a former British foreign secretary who clearly has a head for numbers, put it this way in a New York Times essay: “An American is far more likely to be killed by lightning.” Trump, I’m sure, will get to lightning in due course.

The headline on Miliband’s piece branded Trump’s new policy as ‘Un-American.’ But this is surely wrong. Our country undergoes periodic episodes of extreme intolerance and fear of foreigners, refugees in particular. Not only were Americans of Japanese descent placed in internment camps during WWII, but so were some Italians and Germans. At around the same time, the government — with immense public support — was keeping out Jews and others who were fleeing Hitler. The government has since apologized and paid compensation to surviving Japanese-Americans, but the vein of ugliness has resurfaced. Michael Flynn, Jr., son of Trump’s national security adviser, tweeted the other day: “‘Give me ur tired, ur poor, Ur huddled masses yearning 2 breathe free.’ It’s OUR time as Americans to BREATHE FREE! WE’RE TIRED!” His Twitter account has since been deleted.

Flynn the younger does not speak for the Trump administration, but he seems to have caught its zeitgeist. Our old immigration laws were largely based on crackpot ideas of eugenics and national character that Trump, in some cases, has revived. In his campaign, he referred to Mexicans as rapists, and is now prepared to build a wall to keep them all out of the country, even though few of them are coming. He is turning out to be adept at solving problems that don’t exist.

A former government official I consulted was just plain appalled at what Trump is doing. He pronounced the present system tight, rigorous and safe. Refugees are vetted and then vetted some more. It can take up to three years to gain admittance to this country. Nonetheless, Trump is imposing his new policies as if hordes of terrorists are heading toward Vegas when instead some refugees are seeking to rejoin their families. The new executive order is not only foolish, it is mean.

We have seen something alarming and a bit frightening over the last several days. The Trump administration is inept and indifferent to the suffering it might cause. Even if a new policy is needed, Trump’s people have no idea of how to implement it and the White House seems similarly oblivious to the damage it is doing to America’s image.

Now the world is on notice. The Statue of Liberty, a charming French idea, is being mocked. We will deal cruelly and arbitrarily with refugees, responding to an emergency that does not exist, currying favor with the mob and setting the nation on a new course. Ronald Reagan, quoting the Puritan John Winthrop, referred to America as that “shining city upon a hill.” It took Trump barely a week to tarnish it.

Richard Cohen is a columnist with The Washington Post. His email address is: cohenr@washpost.com.