Whatever the politics of an attack such as this, the human sadness of these sudden and unexpected deaths is always there. Yet America's reaction to the deaths in Nairobi and Dar es Salaam has so far been muted. That is partly because there have been fewer Americans killed than in previous incidents; partly, it is because there is no clear suspect as yet. But it also marks the passing of age: America is more numbed to these attacks than it was 20 years ago, and the way it sees itself and its role in the world is changing.
America's engagement in foreign affairs has always been problematic. It has been almost exactly 100 years since President William McKinley intervened in the war in Cuba against Spain in the name of "the cause of humanity", launching his country into a century of overseas activism. Until then, it had been keener on protecting its own interests at home, secure in the idea of itself as the promised land.
"America does not go abroad in search of monsters to destroy," said John Quincy Adams in 1821. "She might become the dictatress of the world. She would no longer be the ruler of her own spirit." After Cuba, America became a crusader-state which saw itself as engaged in a fight not just for power, but for right.
But it has always been sensitive to the risks and ravages of foreign engagement, and that crusade was interrupted twice: after the horrors of the First World War, and again in the 1970s, as the nation recoiled both from Vietnam and from the stories of the Church Commission's investigation into covert actions abroad. Both times, it was unwillingly led back into the world by Franklin Roosevelt and Ronald Reagan, both of whom believed that it had a duty to engage with its enemies.
Sometimes, that engagement has been very painful. In the past two decades, three events have seared themselves into American minds above all others. There were the harrowing, frustrating days of the Iranian Embassy hostage crisis, and the twisted, charred bodies of those who sought to rescue them. Then there was the crumpled fabric of the Marine barracks in Beirut, destroyed by a truck bomb in 1983, and the soldiers who came to Somalia in a flood of publicity, with arc lights and cameramen on the beach, but many of whom never left.
In the aftermath of these events, each time it was predicted that America would withdraw into itself, unable to absorb the loss. And each time there was a tactical withdrawal, away from the carnage. America is certainly far less willing to put soldiers in jeopardy than it was even 10 years ago. And it remains deeply wary of involvement in theatres such as the Balkans unless a secure exit strategy can be written from the outset. But though America's concern and involvement in foreign policy has diminished since 1989, it remains involved. The much-predicted decline into isolationism has not happened.
Every year, America sends hundreds of thousands abroad to serve in embassies, CIA stations, international development offices, remote listening stations in sleepy Bavarian towns, observation posts on the border between the Koreas and aircraft carriers in the Indian Ocean. The numbers have come down since the end of the Cold War, but the US is still deeply engaged in the world, not just at the level of the think tanks and the high-level dialogues at dining tables in New York, London or Peking, but in terms of a large-scale commitment of people.
Something of the profile of these people can be seen in the casualty list from the Nairobi embassy. Mr Bartley was a career Foreign Service official who had worked his way up from the Brooklyn Boys High School through college, a master's degree and Peace Corps service in Samoa (he had asked for Africa). Many worked for the military, like the fresh-faced 21-year-old Marine Sergeant Jesse Aliganga, or Air Force Master Sergeant Sherry Olds. One, Mary Louise Martin, was an epidemiologist working on a pilot project to treat drug-resistant strains of malaria.
Reading between the lines, some were involved in the more discreet branches of American public service. Molly Huckaby Hardy was an "administrative worker" for the State Department whose family and friends "never actually knew what she did for the government" in Laos, Vietnam, Brazil or Kenya, according to the New York Times. Army Sergeant Kenneth Hobson was sent to Kenya after training in Arabic. "He told his parents he was not allowed to talk much about his job," the New York Times said. Was he, perhaps, one of those in Kenya who were reported to have been monitoring the activities of men linked to the radical Muslim Osama bin Laden?
The assumption of those who bomb American facilities is that the country will react in a certain way: that the US is less willing than others to accept casualties, and that it will inevitably react with a mixture of horrified pain and a desire to strike back that outweighs all rational calculation. This is not unjustified, because that is how America has reacted so often before, when it bombed Libya, or shelled Lebanon from the Second World War battleship USS New Jersey, for instance. It is a nation of outsize emotions.
But the response this time has been more measured, as it was to previous bombings in Saudi Arabia that also claimed American lives. In part, this is a question of policy. Officials from the State Department say publicly that they are quite aware of the risks of over-reaction, and of the dangers that flow from ill-considered if satisfying retaliation in hot blood. But in part it has been because there has been less sense of a public wave of righteous anger, and the need to satisfy it.
Since the Beirut bombings, America has become not immune, but less sensitised to the horrors of sudden strikes on its forces overseas. The World Trade Centre and Oklahoma bombings were also a loss of virginity, showing that terrorism could happen at home as well as abroad.
Oklahoma in particular remains, in the minds of officials and the media alike, a rebuke to those who would leap to judgement on the culprits. Far from being the product of some sinister, faceless Muslim conspiracy, it was the work of a white, Christian American with a grudge against the system. It is not that America has become blase about losing lives in these horrifying events, but it has become more accustomed. And times have changed. During the Cold War, America's government often led the nation further than it wanted to go in foreign policy. The depth of commitment outweighed the public's willingness to be engaged.
This helps to explain both the frequent zig-zags in policy, as the country tried to recalibrate its exposure to foreign affairs, and the cries of pain as engagements that had never properly been explained, or were not sustained by public support, ran into problems.
Commitment and public acceptance are more in balance today. The country has lost a little of its crusading righteousness, but it has also, as a corollary, become less prone to retreat into itself.
Bill Clinton is frequently criticised (from both sides of the Atlantic) for his timidity and reactiveness in foreign policy, but he has a better sense of America's willingness to absorb pain than many of his predecessors. His words after the bombings last week were perfectly in tune with the nation's emotions: grieving at the loss, yet unwilling to be driven back by adversity. Mr Clinton may have many flaws, but as a judge of the public mood, he has perfect pitch.