I had never seen a combat machine gun in a civilian hospital until the day I went to Harare’s Avenues Clinic to visit two women, pro-democracy leaders who had just survived a brutal, methodical beating at the hands of the police.

“We went through unspeakable torture. Each time that night when we heard the sound of boots returning, our bowels loosened,” Grace Kwinjeh said of the ordeal she and Sekai Holland, 64, underwent.

Now they were attempting to heal while under armed guard, hearing those same boots approaching their bedsides intermittently throughout the night.

Zimbabwe’s “3/11” — the day 50 people set out to attend a prayer meeting but ended up suffering hours of torture by security agents — shocked the world and raised hopes that President Mugabe’s impunity might at last be halted.

But barely a month later, the television news cameras are pointing elsewhere, and international leaders are switching off their phones, declining to hear the shrill cries coming out of Zimbabwe. Why?

First, southern African leaders have told the world that the Zimbabwe problem must be left to them to address; and second, the new victims of Mr. Mugabe’s crackdown are “smaller” people — street level pro-democracy organizers, known in their communities but scarcely recognized in the neighboring district, let alone in the wider world.

At least 600 of them have been abducted and tortured by state terror agents this year. Far from being chastened by all the attention, Mr. Mugabe’s regime has stepped up its efforts, invading homes at night, picking off local leaders and activists and taking them to cells in isolated police stations. Officers who protest are court-martialed and transferred to remote stations.

The world has been told — as so often during the past seven years — to put matters in the hands of the president South Africa, Thabo Mbeki, and his quiet diplomacy.

Yet the repression and violence have only intensified since Mr. Mbeki received his mandate from his neighboring heads of state. Far from condemning Mr. Mugabe, they called for the “lifting of all forms of sanctions against Zimbabwe” and insisted that the scandalously rigged elections of the past six years had been free and fair.

Small wonder that Mr. Mugabe was emboldened, and that terror squads now openly brag to their victims that there will be no opposition left by the time of the elections next year.

Does not the international community have a responsibility to protect?

In 2005, the United Nations Security Council rightly decided to discuss Operation Murambatsvina, under which the Zimbabwe government destroyed the homes of 700,000 people and the livelihoods of at least 20% of Zimbabwe’s poor population.

Now, Zimbabwe is again at a point where the U.N. needs to act to end the escalating abductions and torture. South Africa’s U.N. ambassador, Dumisani Kumalo, argues that Zimbabwe’s crisis is not an appropriate matter for the Security Council, because it does not threaten international peace and security.

Yet Mr. Mbeki himself has spoken of the huge humanitarian “burden” on his country as a result of the chaos next door. Indeed, three million Zimbabweans have escaped into neighboring countries, fuelling increased poverty, crime, and xenophobia.

We must learn from history. The U.N. General Assembly’s resolution of September 30, 1974, against South Africa was not premised on apartheid’s threat to security, but on its serious violation of the Universal Declaration of Human Rights.

In U.N. Security Council resolutions passed this year on Somalia, Haiti, the Democratic Republic of Congo, and others, the Security Council has appropriately observed that serious human rights abuses pose a threat to peace and security in the regions where those states are situated. Zimbabwe’s crisis meets this standard.

The secretary general of the U.N., Ban Ki Moon, and his human rights commissioner, Louise Arbor, made a good start when they spoke out about the abuses in Zimbabwe this March.

The U.N. should take the next step by sending in a mission to review, monitor, and call for an end to abductions and torture, and to protect human rights defenders. It is unconscionable that no one, so far, has been willing to try to stop the perpetrators of Zimbabwe’s terror.

Mr. Mutasah is the executive director of the Open Society Initiative for southern Africa.