Last weekend, Marine Corps General James Mattis, the recently retired leader of U.S. Central Command and a man known inside the White House for his sharp opinions (which is one reason he’s no longer leading Central Command) issued a very sharp opinion about Israel’s future.

Speaking at a security conference in Aspen, Colorado, Mattis warned Israel that time was running out for it to reverse its West Bank settlement project.

“We have got to find a way to make the two-state solution that Democrat and Republican administrations have supported, we’ve got to get there,” he said. “And the chances for it, as the king of Jordan has pointed out, are starting to ebb because of the settlements and where they’re at, are going to make it impossible to maintain the two-state option.”

After blaming the lack of peace squarely on the settlements, he went a step further, and raised the incendiary question of apartheid: “If I’m Jerusalem and I put 500 Jewish settlers out here to the east and there’s 10,000 Arab settlers in here, if we draw the border to include them, either it ceases to be a Jewish state or you say the Arabs don’t get to vote — apartheid. That didn’t work too well the last time I saw that practiced in a country.”

Mattis has homed in on the precise issue that alienates liberal-minded Americans and Israelis: the West Bank double standard. Although Israel, within its 1967 borders, is a democracy in which Arabs have legal and voting rights, the West Bank is a two-tiered political entity: Jewish settlers in Hebron have the rights of Israeli citizens, but their Arab neighbors — people who sometimes live mere yards away — are under military occupation, without the same rights. This is a politically and morally untenable arrangement, and Mattis was right to call it out.

He was wrong to blame the lack of peace solely on Israel — the Palestinians have rejected one compromise offer after another, and the Gaza Strip, which would make up about half the future Palestinian state, is under the control of Hamas, which seeks Israel’s elimination — but he isn’t wrong to identify the settlements as an enormous impediment to compromise.

Mattis is also conveying conventional Pentagon wisdom, and this is why the settlers, and their advocates in the cabinet of Prime Minister Benjamin Netanyahu, ought to be paying close attention, because they can’t forever stand against the opinions of men like Mattis (who, by the way, couldn’t be considered “anti-Israel” by any stretch of the imagination).

Mattis went on to make another assertion that Netanyahu’s cabinet ought to heed: “I paid a military security price every day as the commander of Centcom because the Americans were seen as biased in support of Israel and that moderates all the moderate Arabs who want to be with us, because they can’t come out publicly in support of people who don’t show respect for the Arab Palestinians.” He went on to say that John Kerry, the U.S. secretary of state who’s trying to restart peace talks, “is right on target with what he’s doing. And I just hope the protagonists want peace and a two-state solution as much as he does.”

Arab rulers who complain about U.S. support for Israel to generals like Mattis are playing their American counterparts a bit: It’s very hard to imagine the Saudis and the Emiratis and the Kuwaitis and the Jordanians not taking American help — or not providing bases to the U.S. — because they’re upset by settlements. The Arabs uniformly fear and loathe Iran more than they fear and loathe Israel. Still, it’s true that American military commanders wouldn’t have to sit through quite so many lectures about Palestinian rights if there was movement on the peace process. It’s also true that men like Mattis make their own weather — that is, whether he’s right or wrong, this is what he believes, and it would be foolish for the Israelis, a dependent power, to ignore the feelings of powerful American generals.

What Israeli army generals know — and what many of their political leaders don’t seem to recognize — is that Mattis’s views are commonplace in the American defense establishment. The Israeli right can only ignore this reality for so long without doing its country permanent damage.

Jeffrey Goldberg

Jeffrey Goldberg is a columnist for Bloomberg View, and a senior editor at The Atlantic.