UNBURDENED BY facts and seduced by a swelling hysteria after the carnage last week in Paris, Mayor David Bowers of Roanoke called Wednesday on local resettlement agencies to spurn any Syrian refugees who might be placed in his region. As rationale, he cited President Franklin D. Roosevelt’s order after Pearl Harbor to imprison Japanese Americans, most of them citizens, a disgraceful episode for which President Ronald Reagan signed legislation in 1988 formally apologizing and authorizing cash payments to surviving victims.

Mr. Bowers, a Democrat, thus joined 26 governors, all but one of them Republican, in an ugly national panic, fanned by demagoguery, to try to ban Syrian refugees who in most cases were driven from their homes by the very brand of violence they are now baselessly suspected of seeking to propagate in the United States.

American history is rich in fearful episodes often but not exclusively directed at foreigners. The Red Scare of the 1950s shared roots with the vilification of Germans after Chicago’s Haymarket bombing in 1886; in both cases, Americans were whipped into a furor by the specter of enemies within.

The same impulse now unhinges officials such as Gov. Mike Pence of Indiana, a Republican, who rolled up the welcome mat, prompting resettlement agencies to divert a family of three Syrian refugees — including a young boy and his father, who ran a used-clothing store in his home country — to Connecticut.

It is legitimate to demand thorough screening of refugees. By contrast, it was political posturing by the House of Representatives to pass a bill Thursday, backed by the GOP and about 50 Democrats, requiring that the FBI director, the homeland security secretary and the director of national intelligence confirm that each applicant from Syria and Iraq poses no threat.

A reality-based response to the threat posed by the Islamic State would direct extra scrutiny at the estimated 3,000 Europeans — mainly French, British and Belgian — who have traveled to Syria in the past two years. Of the nine suspected assailants in Paris, at least six were either French or Belgian citizens, not Syrians. Another might have been a Syrian who entered Europe as a refugee — possibly — although it was unclear whether the passport found near his body was genuine.

In the past year, Germany has welcomed nearly 100,000 Syrian refugees, an impressive act of humanitarianism that shamed President Obama into authorizing 10,000 to enter the United States in the coming year. By comparison, the United States accepted fewer than 1,700 Syrian refugees in the most recent fiscal year.

In one sense, Mr. Bowers was absolutely right in comparing Japanese Americans during World War II with Syrian refugees today: The frenzy directed against them arises from “race prejudice, war hysteria, and a failure of political leadership.” That language is in the bill passed by Congress in 1988 apologizing to Japanese Americans. It is depressing to imagine a generation from now children asking the same question about yet another chapter in U.S. history: How could that possibly have happened here?