The recent horrific bombings in Bali should not obscure a far larger, institutionalized Indonesia-associated set of horrors. It was born forty years ago this month when the Indonesian army initiated what the U.S. Central Intelligence Agency described as "one of the worst mass murders of the 20th century." Four decades later, the failure to hold anyone accountable for the slaughter--or, in places like the United States, even to remember it--continues to have negative repercussions for human rights.

Under Major General Suharto's leadership, the army and its civilian militia groups used an alleged coup attempt on October 1, 1965 as an excuse to round up and kill hundreds of thousands of members of the Indonesian Communist Party (PKI), and of loosely affiliated organizations such as women's groups and labor unions.

Despite the magnitude of the carnage, Marshall Green, American ambassador to Indonesia at the time, wrote that the embassy had "made clear" to the army that Washington was "generally sympathetic with and admiring" of its actions.

U.S. support for the killings was rooted in Washington's longstanding wish to have unimpeded access to Southeast Asia's great wealth of strategic resources such as oil, rubber, and tin. World War II, the disruption of European colonial rule, and the emergence of the United States as the post-war regional power provided the opportunity to realize that desire.

But new obstacles arose when the Sukarno government emerged upon independence in Indonesia--the country many in Washington saw as the region's centerpiece. Sukarno's domestic and foreign policy was nationalist, nonaligned, and critical of Western intervention. Moreover, his government had a working relationship with the powerful PKI, which Washington feared would eventually win national elections. For these reasons the Eisenhower administration conducted covert operations to destabilize Indonesia, efforts that culminated in 1965-66 with the PKI's eradication and Sukarno's effective overthrow.

U.S. policy had helped lay the groundwork for the killings through support for anti-communist elements of the military, and intelligence operations aimed at weakening the PKI and drawing it into conflict with the army. So when the army began the killings, the Johnson administration supplied it with weaponry and telecommunications equipment, and, once Suharto had formally assumed power, provided food and other aid. The U.S. Embassy also gave the names of thousands of PKI cadre who were subsequently executed.

The PKI's destruction and Sukarno's ouster resulted in a dramatic shift in the regional power equation, leading Time magazine to hail Suharto's takeover as "The West's best news for years in Asia." Meanwhile, the U.S. Navy League's publication gushed over Indonesia's new role in Southeast Asia as "that strategic area's unaggressive, but stern, monitor."

Ten years later, Suharto's "unaggressive" Indonesia invaded neighboring East Timor after receiving permission from the Ford administration. The war and almost 24-year illegal occupation cost tens of thousands of East Timorese lives. Within Indonesia proper, Jakarta's military has committed myriad additional atrocities--from killing tens of thousands in independence-seeking West Papua to thousands more in the oil-rich Aceh region.

With Suharto's resignation in 1998, significant political space has opened up in Indonesia resulting in competitive national elections, but the armed forces still loom large over the state apparatus. And no military or political leaders have been held responsible for the post-Sukarno-era crimes, thus increasing the likelihood of future atrocities and aggression--a source of continuing worry for Indonesia's civil society and restless regions, as well as poverty-stricken, now-independent East Timor.

Here in the United States, despite political support and billions of dollars in weaponry, military training and economic assistance to Jakarta over the preceding four decades, Washington's role in Indonesia's killing fields of 1965-66 and subsequent brutality has been effectively buried. Such "forgetting" has translated into a lack of accountability for U.S. complicity in these crimes, while enabling the Bush administration's current efforts to further ties with Indonesia's military, as part of the global "war on terror."

The continuation of this dangerous alliance, and the impunity that underlies it, can only lead to further atrocities--in Indonesia and elsewhere--as it has for the last forty years.

Joseph Nevins is an assistant professor of geography at Vassar College and author of A Not-so-distant Horror: Mass Violence in East Timor (Cornell University Press, 2005).