Diane Rehm’s nationally syndicated talk show is known for its mild-mannered approach to weighty policy topics. So Rehm’s exchange with Democratic presidential candidate Bernie Sanders on Wednesday, June 10 struck many listeners as jarring.

Rehm: "Senator, you have dual citizenship with Israel."

Sanders: "No, I do not have dual citizenship with Israel, I'm an American. Don't know where that question came from. I'm an American citizen. I have visited Israel on a couple of occasions. No, I'm an American citizen, period."

Rehm: "I understand from a list we have gotten that you were on that list. Forgive me if that …"

Sanders: "No, that's some of the nonsense that goes on in the Internet. But that is absolutely not true."

Rehm: "Interesting. Are there members of Congress who do have dual citizenship or is that part of the fable?"

Sanders: "I honestly don't know. But I have read that on the Internet. You know, my dad came to this country from Poland at the age of 17 without a nickel in his pocket. He loved this country. I am, you know, I got offended a little bit by that comment, and I know it's been on the Internet. I am, obviously, an American citizen and I do not have any dual citizenship."

The exchange was noticed by Jared Sichel in a blog post for the Jewish Journal, a California newspaper. Sichel tracked down a mention of Sanders being a dual citizen in the comments section of a Facebook page, where a user had posted a list of senators and representatives who "have both Israel and U.S. citizenships."

"No source is given," Sichel wrote, "because the list is a total fabrication, not to mention created by an anti-Semite and anti-Zionist, which is given away by the fact that it says ‘Jewish Lobby,’ ‘#israelwarcrime,’ ‘AIPAC: Buying Congress one seat at a time,’ ‘Rothschild,’ and features an American flag with a Star of David replacing the 50 stars."

After that, news of Rehm’s interview went viral, with many asking why she had relied on such questionable material. The Anti-Defamation League, which combats anti-Semitism, issued a statement calling the episode "deeply troubling" and saying that the source material played into "classic anti-Semitic charges of dual loyalty."

Rehm later issued an apology:

"On today's show I made a mistake," she wrote. "Rather than asking senator and presidential candidate Bernie Sanders whether he had dual U.S./Israeli citizenship, as I had read in a comment on Facebook, I stated it as fact. He corrected me, saying he did not know where the question came from. I apologized immediately. I want to apologize as well to all our listeners for having made an erroneous statement. I am sorry for the mistake. However, I am glad to play a role in putting this rumor to rest."

In reality, the claim that a wide variety of high political officials, including members of the House and Senate, are actually dual U.S./Israeli citizens have been circulating around the Internet for the better part of a decade.

We figured it was a good time to take a closer look at the issue.

What’s appeared on the Web

From what we can tell, lists claiming that top Jewish political officials were "dual citizens" with Israel first began to pop up in the wake of the Iraq War. At the time, they were focused on the notion that Jewish officials in the administration of President George W. Bush had pushed for war in the Middle East at the behest of Israel.

For instance, a Facebook post titled, "List of Politicians with Israeli Dual Citizenship," appeared as early as 2007 and was periodically reposted later. It discussed the pro-Israel "lobby" and its efforts to push "policies which can be viewed as in direct opposition to the interests and security of the American people," through the assistance of "U.S. government appointees who hold powerful positions and who are dual American-Israeli citizens."

The post listed more than three dozen such "dual Israel-American citizens," including attorney general Michael Mukasey, former Pentagon officials Paul Wolfowitz and Douglas Feith, White House officials Josh Bolten and Ken Mehlman, and a host of ambassadors. The common thread, apparently, was that they all were, or were believed to be, Jewish.

Sanders wasn’t on this initial list, but his name began appearing around 2012 in a variety of posts with headlines such as "Israeli Dual Citizens in the U.S. Congress and the Obama Administration." A common version included 22 officials currently or previously with the Obama administration, 27 House members and 13 senators, including Sanders.

The authors of these posts cribbed their list of Jewish lawmakers from a 2011 article in Jewish Currents, "a non-profit, progressive Jewish media project." The Jewish Currents article acknowledged that some of its readers -- who are generally left of center -- might be "nervous" about drawing attention to Jewish lawmakers.

Such caution may have been merited. In one case, a version of the list of politicians with "dual U.S./Israeli citizenship" was posted on the website of the American Freedom Party, an organization that fights for the heritage, identity and rights of "ethnic European communities."

Are Jewish-Americans automatically Israeli citizens?

The key assumption in all of these posts -- that if someone is Jewish, they are automatically a citizen of Israel -- is simply wrong.

It stems from a misreading of the Law of Return, originally passed by Israel in 1950 and subsequently amended. According to the law, with a few exceptions, an immigration visa "shall be granted to every Jew who has expressed his desire to settle in Israel." A certificate of citizenship will be granted to those who wish to live in Israel permanently.

In other words, a Jewish-American (whether politician or not) will typically be granted Israeli citizenship if they seek it out. Israeli citizenship is not conferred to them simply by being Jewish.

Adding to the confusion, some of the commentary we found on the Internet suggested that any Jewish person received Israeli citizenship automatically once they touched down on Israeli soil. If that were true, then any lawmaker who went on an official visit to Israel -- and many of them have -- would have become a dual citizen, perhaps without even knowing it.

This, too, is not true.

Applying for citizenship under the Law of Return "is a formal procedure which you could expect normally to take a number of months except under emergency conditions," said Yoram Hazony, president of the the Herzl Institute, a Jerusalem think tank. "There is no such thing as receiving Israeli citizenship without submitting a formal request to the Israeli government."

Indeed, guidance from the Jewish Agency -- a nonprofit group that coordinates immigration into Israel -- lists a number of required steps, including an online application, the filing of documentation, and an interview. (The Israeli Embassy in Washington did not return emails for this article.)

Yigal Palmor, a spokesman for the Jewish Agency, told PunditFact that "to contend that citizenship is granted automatically by simply setting foot on Israeli soil is beyond preposterous. There's no such procedure anywhere in the world and it could not be implemented even if anyone wanted to, for legal, administrative and practical reasons."

It’s also worth noting that the U.S. government doesn’t look especially kindly on dual citizenship. The United States "recognizes that dual nationality exists but does not encourage it as a matter of policy because of the problems it may cause," according to the Department of State. If an American citizen applies for foreign citizenship voluntarily, they "may lose U.S. nationality," if there is evidence, through their statements or conduct, that they intend to give up their U.S. citizenship.

Sanders’ case

So has Sanders ever taken action to claim the Israeli citizenship the would qualify for? He told Rehm no, and we have no evidence that would call that into question. While Sanders is Jewish by birth and spent some time on an Israeli kibbutz, or community farm, in the early 1960s, he would not have become a citizen without a concerted effort to become one.

We did not hear back from Sanders’ office, but a spokesman, Michael Briggs, told Politico that "Diane Rehm is an excellent radio host. There’s a great big Internet out there with lots of good and bad information. I’ve never heard the question come up before."

Hazony, an Israeli who studied at Princeton and Rutgers and who has written widely about both American and Israeli politics, said he’s not aware of any American lawmakers with Israeli citizenship. "In fact, it is common for Jews who are dual U.S.-Israel citizens to renounce one or the other before serving in official government capacities," he said.