President Donald Trump’s missile strike against Syria inaugurates a new chapter in the long and controversial history of American responses—and sometimes non-responses—to mass murder around the world.

Although the killing of Syrian civilians by President Bashar al-Assad’s regime does not technically constitute genocide—which the United Nations defined in 1948 as the “intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such”—there is no doubt Assad has committed heinous and large-scale war crimes. 

Trump’s decision to order missile strikes on Syria was primarily motivated by humanitarian concerns over Assad’s latest chemical attack on Syrian civilians, although Trump also cited the danger to U.S. interests posed by chemical weapons proliferation.

How does Trump’s action compare to past U.S. responses to genocide? Here is a sampling:

Islamic State

Under congressional pressure in 2015, the Obama administration belatedly declared that the atrocities committed by the Islamic State terror group against Yazidis, Christians and other non-Muslim minorities in Syria and Iraq constitute genocide. The administration’s decision did not, however, result in any change in the U.S. policy of limited air strikes against Islamic State.

Libya

In response to attacks on Libyan civilians by Muammar Qaddafi in early 2011, President Barack Obama authorized U.S. participation with its allies in air and naval strikes against the Libyan leader. Citing the weak international response to Bosnia, Obama said intervention in Libya was necessary to prevent “a massacre that would have reverberated across the region and stained the conscience of the world.” Qaddafi was killed and his regime was overthrown. 

Darfur

President George W. Bush saw no compelling reason to intervene in the Sudanese government’s mass murder of an estimated 500,000 non-Arab civilians in the Darfur region, which began in 2003. The Bush administration also initially resisted congressional calls to categorize the killing as genocide. President Obama continued the policy of non-intervention in Darfur. The International Criminal Court in 2009 indicted Sudanese leader Omar al-Bashir on genocide charges, but the Obama administration declined to seek his arrest or to establish a no-fly zone over Sudan, despite ongoing atrocities.

Rwanda

The Clinton administration was aware, in real time, of the slaughter of 800,000 ethnic Tutsis by Hutu death squads in Rwanda in early 1994. Susan Rice, then director of African Affairs for the National Security Council, opposed U.S. intervention because of its possible “effect on the November [congressional] elections.” At the urging of then-U.N. ambassador Madeleine Albright, the United States supported withdrawal of international peacekeepers in Rwanda who were thought to be in danger. Ironically, Albright later co-chaired the Genocide Prevention Task Force for the Obama administration.

Bosnia

Legal scholars adopted the term “ethnic cleansing” to characterize the widespread atrocities in the Balkans war of 1992-1995, which were carried out primarily by Serbs against Muslims. President Bill Clinton initially resisted U.S. intervention, but in response to a July 1995 massacre of 8,000 Bosnian Muslims, Clinton authorized U.S. participation in NATO airstrikes. The bombing campaign resulted in the warring parties negotiating an end to the conflict.  

Cambodia

In the wake of the unpopular Vietnam War, Presidents Gerald Ford and Jimmy Carter declined to intervene when the newly victorious communist regime in Cambodia, the Khmer Rouge, carried out the mass murder of an estimated 2 million civilians (many of whom were targeted as ethnic and religious minorities) from 1975-1979.

The Holocaust

The Franklin D. Roosevelt administration rejected requests to bomb the Auschwitz death camp or the railway lines leading to it, claiming such action would require diverting American planes from battle zones. In reality, U.S. planes in 1944 repeatedly bombed German synthetic oil fields adjacent to Auschwitz, some of them less than five miles from the gas chambers. The real reason the administration declined to take such military action was its fear—as one senior State Department official put it—of “the danger that the German government might agree to turn over to the United States and to Great Britain a large number of Jewish refugees.”

The U.S. bombing of Budapest in the summer of 1944, although unrelated to the mass killing of the Jews, did unintentionally affect the murder process. Hungarian officials intercepted messages from local Jews pleading for U.S. military intervention, and mistakenly concluded that the U.S. strikes on Budapest were in response to the deportation of Hungarian Jews to Auschwitz. As a result, Hungary belatedly halted its cooperation with the deportations, bringing them to a halt.

Armenia

The idea of U.S. intervention against atrocities abroad first arose during Turkey’s World War I-era slaughter of more than 1 million Armenians. Then-former President Theodore Roosevelt urged declaring war on Turkey. “The failure to deal radically with the Turkish horror means that all talk of guaranteeing the future peace of the world is mischievous nonsense,” he warned in 1918.

Roosevelt’s plea attracted few supporters. To this day, successive presidents have declined to publicly acknowledge that the killings constituted genocide, over fear of upsetting U.S.-Turkey relations. The sensitivity of the issue was further illustrated by the Obama administration’s refusal, for more than a year, to display a handwoven rug sent by Armenian orphans to the White House in 1925 in appreciation for America’s postwar aid. 

Looking ahead

This month’s commemoration of Holocaust Memorial Day (Yom HaShoah) will be the occasion for much discussion concerning the contrast between America’s traditionally meager response to genocide, and the dramatic U.S. action in Syria. Was the missile attack a one-time gesture, or does it represent a substantive change in American policy? Time will tell.