Refugee vetting has an excellent record. Of 785,000 refugees admitted to the United States since 9/11, just three have been arrested for terrorism-related charges, according to the Migration Policy Institute in Washington.

If Republican governors are concerned about security risks, maybe they should vet who can buy guns. People on terrorism watch lists are legally allowed to buy guns in the United States, and more than 2,000 have done so since 2004. The National Rifle Association has opposed legislation to rectify this.

Although Donald Trump fulminates about President Obama supposedly wanting to bring in 250,000 or more Syrian refugees, that’s preposterous: Obama proposes admitting 10,000 Syrian refugees over a year. That’s tiny, just 1 percent of the number that Lebanon has accepted.

The Islamic State is trying to create a religious divide and an anti-refugee backlash, so that Muslims will feel alienated and turn to extremism. If so, American and European politicians are following the Islamic State’s script.