If truth is the first casualty of war, it can also take a beating in a time of terrorism. A week of raging debate over Syrian refugees and Islamic State violence has scattered misinformation everywhere.

In the Republican presidential contest, Donald Trump found himself with a potential new rival, the Constitution, in calling for a registry of Muslim citizens. Jeb Bush described a religious test for refugees that does not represent the actual law.

In Congress and among governors, some Republicans overstated thin evidence of a link between Syrian refugees and terrorists in Europe. Some Democrats — President Barack Obama among them — may have been too quick to dismiss the risk that such radicals will infiltrate the dispossessed and slip past a U.S. security apparatus that has proved leaky in the past.

To be sure, there are many unsettled facts in the chaotic aftermath of the attacks that killed 130 people in Paris and set U.S. leaders, as well as the public, on edge. But some things are known.

A look at some of the claims over the past week and how they compare with reality:

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TRUMP: "Our president wants to take in 250,000 from Syria."

THE FACTS: Not even close, but Trump routinely throws out the figure anyway.

Obama has expanded the usual annual ceiling for refugees of 70,000 by an additional 15,000, with 10,000 of those new slots for Syrians. At the outset, officials said this program for Syrian refugees probably would continue beyond one year. But nothing approaching 250,000 is in the cards.

Trump also states that most of the people leaving Syria are men, with very few children, an observation he made at one point by seeing the crowds on TV.

But of the roughly 2,000 Syrian refugees who have come into the U.S., the State Department says that half are children, one-quarter are over age 60, the sexes are split about equally, and only 2 percent are single men of combat age.

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BUSH: "In the law, it requires a religious test. ... It is a requirement, as you go through the screening process, that religion is an element to it."

THE FACTS: No religious test is required for people seeking asylum or refugee status.

The law does offer religious persecution as one of five broad grounds for granting asylum or refugee status. Those who would have their life or freedom threatened on account of their religion could qualify. So could those facing persecution because of their race, nationality, political opinions or associations with social groups.

So, religion can be an element the government considers, if someone cites it as a reason to seek refuge, but it is not a test in law.

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OBAMA on Republicans: "Apparently they are scared of widows and orphans coming into the United States." On Syrian refugees: "They are subjected to the most rigorous process conceivable."

THE FACTS: Obama's mocking of Republicans worried about terrorists slipping into the U.S. with authentic refugees masks concerns that were expressed by his own administration about that very potential before the Paris attacks.

James Clapper, director of national intelligence, told a security conference in September: "As they descend on Europe, one of the obvious issues that we worry about, and in turn as we bring refugees into this country, is exactly what's their background? We don't put it past the likes of ISIL to infiltrate operatives among these refugees," he said, using an acronym for the Islamic State group. Clapper added, "That is a huge concern of ours."

He went on to cite America's "pretty aggressive program" for screening newcomers. But he was not alone in acknowledging risks.

In congressional testimony in October, FBI Director James Comey told lawmakers "the good news is we have improved dramatically our ability as an interagency — all parts of the U.S. government — to query and check people," since a troubled program for vetting refugees from Iraq.

"The bad news is our ability to touch data with respect to people who may come from Syria, may be limited," he said. "That is, if we don't know much about somebody, there won't be anything in our database." He said a decade of U.S. involvement in Iraq yielded background that is "richer than the data we have from Syria."

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TRUMP, on requiring Muslims in the U.S. to register in a database: "They have to be ... absolutely."

THE FACTS: Constitutional scholars say good luck with that.

The main thrust of Supreme Court cases has been to cast doubt on religious, racial, religious and gender classifications. You can't discriminate against a class of people, and the court looks hard at even neutral-sounding policies that are a pretext for discrimination. Based on this history, it might be OK to focus on a group of extremist Muslims, but not on all Muslims.

As far as religion goes, the Supreme Court ruled in 1947 in a case about taxpayer subsidies of bus service for Catholic children. In that opinion, Justice Hugo Black wrote that the First Amendment prohibits the federal and state governments from passing laws that "aid one religion, aid all religions or prefer one religion over another."

"No person can be punished for entertaining or professing religious beliefs or disbeliefs, for church attendance or nonattendance," he wrote.

A decision that seems out of step with the bar on discrimination, upholding internment of Japanese-Americans in World War II, has never been overruled, but has been thoroughly discredited. Almost every justice who has opined on it has called it wrong. But one of those critics, Justice Antonin Scalia, has also said something like it could happen again. He used a Latin phrase that roughly translates as "in times of war, the laws fall silent."

Even so, any step that would both single out a group for classification and intrude on religion would face highly improbable odds before the Supreme Court.

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GOV. MIKE PENCE of Indiana: "Last week, one of the terrorists who perpetrated the attacks in Paris exploited the European Union's refugee system to gain entrance to France.

THE FACTS: That may turn out to be so, but Pence's conclusion — widely shared by lawmakers who pressed for a suspension of Obama's program for Syrians — is ahead of the established facts.

Most of the known attackers were French or Belgian. Authorities are still investigating whether one may have come from Syria with refugees and whether any tie exists between the masses flowing into Europe and the terrorists who carried out the assault.

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Associated Press writers Mark Sherman, Deb Riechmann and Alicia A. Caldwell in Washington and Jill Colvin in Spartanburg, South Carolina, contributed to this report.