You’ve probably read about the situation in the West Bank city of Hebron, where some 800 Jewish settlers live in the midst of 170,000 Palestinians. But being there is something else. Being there can make you sick to your stomach; being there you can’t help thinking of the “A-word.”

A few weeks ago, I spent an afternoon in places you won’t find on most synagogue tours, and there is no other word to describe what I saw. In the settlement of Kiryat Arba, Hagit Ofran, director of Peace Now’s Settlement Watch project, told our delegation from Americans for Peace Now, “From here, only Israelis can enter Hebron by car; Palestinians have to go on foot.” I thought she was joking. She wasn’t.

Since the 1970s, radical settlers have been reclaiming properties in Hebron that were owned by Jews prior to the establishment of the state in 1948. Today, there are signs everywhere proclaiming the settlers’ God-given right to the city, citing the words of the Torah (“The children have returned to their own border.” Jeremiah 31:17) and recalling the 1929 massacre of 66 Jews by their Arab neighbors.

I saw no mention of the 1994 massacre that took place at the Ibrahimi Mosque in the Tomb of the Patriarchs, where Baruch Goldstein, an American-born Israeli doctor, opened fire on Muslim worshippers, killing 29 and wounding 125. When the streets of Hebron erupted with rage, the Israel Defense Forces imposed a curfew on the Palestinians, confining them to their homes for all but a few hours a day to buy food.

First we’re massacred, then we’re punished, was the incensed Palestinian response. Why not put the Jewish extremists under curfew? Why does the burden of Jewish security always fall on us?

With each new outburst of violence, the Israeli army imposed more restrictions on the Palestinians. The Hebron Protocol of 1997, a diplomatic accord reached by Israel and the Palestine Liberation Organization with the help of the Clinton administration, formally divided the city. Palestinians were given responsibility for the lion’s share of greater Hebron, called Area H-1, while Area H-2 — the 18% of the city in which the settlers had inserted themselves — remained under Israeli military control.

The vast market that had served the city and surrounding villages fell in H-2. It was shut down by the Israeli army, and separation measures were imposed to protect the settlers against attack and further reduce friction between Arabs and Jews. Palestinians’ access to the center of town was severely restricted, their shops closed, a few stores taken over by settlers, most boarded up.

Now, after 14 years, the main street looks like a ghost town, its crumbling buildings scarred with Hebrew graffiti: “Jews Only Buy From Jews.” “No Arabs, No Mice.” “Death to the Arabs!” and worse. My stomach heaved at the hate-filled words but even more so at the sight of the street split by a physical divider, one side for Palestinians, the other for Jews — the larger side for Jews — with Israeli soldiers on guard over the scene. Ofran said some Palestinians, because they cannot use the streets, must reach their homes via their neighbors’ rooftops.

In 10 breathless minutes, Issa Amro, a Palestinian human rights activist we met, drew a chilling portrait of Israeli occupation of H-2 and its 18 checkpoints. Though born in Hebron, he is not allowed on some of the streets. Though he practices nonviolence, he is subject to military law, while even the most violent and radical settlers live under civil law. He told us of how Palestinians can be detained without trial for days, Israelis for only 24 hours. Palestinians have to fence their windows to ward off settlers’ rocks; the army fails to protect their homes. He recounted how two years ago a woman gave birth at a checkpoint because Palestinian ambulances need special authorization to cross between the two sectors. Dozens of roads have been blocked with cement barriers to prevent Palestinians from moving freely.

If one opens one’s eyes to the truth, the unmentionable becomes unavoidable — “A” for arrogance, and yes, for apartheid. It hurts me just to write that word.

As a life-long, Israel-loving, peace-seeking Zionist, I disdained the hyperbolic label and the facile, incendiary parallels to pre-Mandela South Africa that, for years, have been propagated by Jimmy Carter and some pundits on the left. I’ve made at least two dozen trips to Israel since 1976 and, though strongly critical of its government’s policies toward Palestinians within and outside the Green Line — whether under Labor, Likud or Kadima leadership — I never felt that extreme indictment was warranted by the facts on the ground. Then again, until last month, I had never been to Hebron.

Justice-loving Jews cannot keep denying what is happening under Israeli auspices in Hebron; we can never say we didn’t know.

Letty Cottin Pogrebin, a founding editor of Ms. Magazine and the author of nine books, is a past president of Americans for Peace Now.