Bernie Sanders went on offense during Thursday’s Democratic primary debate, criticizing Hillary Clinton for “barely mentioning” the Palestinian people during her speech before the American Israel Public Affairs Committee, the nation’s most powerful pro-Israel group, last month.

Sanders, the independent senator from Vermont, and Clinton, the former secretary of state, largely agree about the Israeli-Palestinian conflict. They both believe Israel has the right to exist as a Jewish and democratic state and that the Palestinian people should have a state of their own.

On Thursday, Sanders doubled down on his past argument that Israel's invasion of Gaza in 2014 in response to rocket attacks was "disproportionate," said the U.S. and Israel need "to treat the Palestinian people with respect and dignity" and argued that the U.S. "cannot continue to be one-sided." While each of these comments is a bold thing to say on a Democratic primary debate stage, the real historic moment was the exchange between the two candidates over how Clinton talks about Palestinians and whether the U.S. grovels to Israeli Prime Minister Benjamin Netanyahu too frequently.

“I read Secretary Clinton’s speech before AIPAC. I heard virtually no discussion at all about the needs of the Palestinian people,” Sanders said. “Of course Israel has a right to defend itself, but long-term, there will never be peace in that region, unless the United States plays an even-handed role, trying to bring people together and recognizing the serious problems that exist among the Palestinian people ... There comes a time when, if we pursue justice and peace, we are going to have to say that Netanyahu is not right all of the time.”

SAUL LOEB/AFP/Getty Images Hillary Clinton speaks during the American Israel Public Affairs Committee (AIPAC) 2016 Policy Conference at the Verizon Center in Washington, D.C., March 21, 2016.

Clinton told AIPAC in March that “Palestinians should be able to govern themselves in their own state, in peace and dignity,” and that “Everyone has to do their part by avoiding damaging actions, including with respect to settlements.” But she used the vast majority of her time to talk about defending Israel’s security, strengthening the U.S.-Israel alliance and holding Iran accountable. Sanders passed on speaking to AIPAC in person and instead gave his speech at a high school in Utah. He talked about Palestinian unemployment and poverty, dedicated more than a sentence to condemning Israeli settlement construction in the West Bank and criticized groups like AIPAC for trying to torpedo the nuclear deal with Iran.

Shibley Telhami, a professor at the University of Maryland, College Park, and non-resident senior fellow at the Brookings Institution, told The Huffington Post that the debate about how the U.S. should resolve the Israel-Palestine conflict was “unprecedented.”

“It wasn’t only that he highlighted the need to address the Palestinian issue and Palestinian rights, it is that he turned it into an asset -- rather than be on defense he put Hillary Clinton on the defensive for not bringing it up in her AIPAC speech,” he said.

Telhami, who served as a senior advisor to George Mitchell, Obama’s special envoy for Middle East peace, said that there is a gap between how Democratic politicians talk about the conflict and what the party’s grassroots believes. Sanders capitalized on that disconnect.

Somebody was bound to come along who is far more reflective of grassroots politics than Democratic candidates have been. Shibley Telhami

“When Sanders gave the non-AIPAC AIPAC speech, we saw that it didn’t hurt him in the next series of primaries and caucuses where he won overwhelmingly and generated a lot of enthusiasm,” he said. “This is new, but I think it’s an inevitable consequence of the public opinion transformation -- somebody was bound to come along who is far more reflective of grassroots politics than Democratic candidates have been.”

Sanders is reticent to discuss foreign policy instead of his core issues of income inequality and political corruption, and tends to do so only to criticize Clinton for her Iraq War vote or for the intervention in Libya. (He got into a shouting match with critical constituents of his during a town hall in 2014, yelling that he was sorry he didn’t “have the magic answer” to the conflict because “this is a very depressing and difficult issue.”)

Progressive supporters of Sanders have voiced frustration with the senator in the past for not condemning Israel more forcefully -- and they’re more furious after his campaign suspended its new Jewish outreach director for her past critical comments accurately describing Netanyahu’s personality. His debate performance may partially ameliorate those feelings.

George Frey/Getty Images Democratic presidential candidate Bernie Sanders spoke at a campaign rally at West High School on March 21, 2016 in Salt Lake City, Utah, instead of at AIPAC.

“Last night was an important moment for many of us who would like to see a more reality-based discussion of U.S. Middle East policy,” said Matthew Duss, president of the Foundation for Middle East Peace. “Posing that equality [between Israeli security and Palestinian security] is something that’s new -- it’s something a lot of Americans believe but we haven’t heard a candidate articulate it as strongly as that before.”

Duss suggested that the Clinton-Sanders exchange happened because today, unlike in previous campaigns, there's a counterweight to AIPAC in the American Jewish community. Advocacy groups like J Street emphasize that it’s possible to be a supporter of Israel and criticize the Israeli government’s actions.

“Political constituencies that organize well and make their concerns heard get responded to. For a long time, a very conservative, hawkish pro-Israel constituency has been much better organized, but that’s changing,” Duss said. “People who support peace and security for both Israelis and Palestinians equally have become much better organized. Seeing the security of both peoples as tied together and not in tension is much more in keeping with American liberal values.”

People who support peace and security for both Israelis and Palestinians equally have become much better organized. Matthew Duss

Some foreign policy experts active on Twitter -- like Jeffrey Goldberg, the Atlantic’s national correspondent -- have argued in response to pieces in The New Yorker and Vox that Sanders’ comments on Palestinian dignity during the debate weren’t that revolutionary or new. His statements, they showed, reflect the same sentiments as words spoken by Obama and former presidents Bill Clinton and George W. Bush. But it’s different for a presidential candidate to talk about Palestinian rights. Candidate Obama was much more cautious and conservative on this issue than President Obama has been, for instance.

The dynamics of the conflict have shifted. Former presidential candidate and Vermont Gov. Howard Dean (a Clinton supporter) was excoriated by then-Sen. Joe Lieberman (D-Conn.) and other Democrats during the 2004 primary when Dean said the U.S. should be “even-handed,” that "it's not our place to take sides" and that "enormous" numbers of Israeli settlements in the territories would have to be dismantled to achieve peace.

Twelve years later, a different situation is at hand. During Thursday's debate, the insurgent candidate in the race was able to push the front-runner to say that “Nobody is saying that any individual leader is always right.”

Jews, who will make up a significant share of New York’s Democratic primary electorate on Tuesday, aren’t used to hearing either explicit or implicit criticisms of Netanyahu as their votes are sought.

Bernie Sanders didn’t really say anything extraordinary about the Palestinians, but his statements at the Democratic debate on Thursday were historic nonetheless, at least for them … The true novelty in Sanders’ words was that they violated accepted norms. Presidential candidates usually swear on an Israeli bible before they get elected into office and discover Palestinian suffering only after they have moved into the White House: this is the road travelled by Jimmy Carter in 1976 and by Barack Obama in 2008.