Latest horror could destroy President of divided nation

Is this the horror that will finally undo George Bush's presidency? First Nicholas Berg, now Paul Johnson: in two months and in two different countries, two US civilians have been kidnapped and beheaded by their al-Qa'ida-affiliated captors, becoming not only pawns in a deadly geopolitical game but also symbols of the complicated feelings of revulsion unleashed by the Bush administration's "war on terror".

Is this the horror that will finally undo George Bush's presidency? First Nicholas Berg, now Paul Johnson: in two months and in two different countries, two US civilians have been kidnapped and beheaded by their al-Qa'ida-affiliated captors, becoming not only pawns in a deadly geopolitical game but also symbols of the complicated feelings of revulsion unleashed by the Bush administration's "war on terror".

It is hard not to think back to earlier acts of defiance against the might of the United States and wonder if we are not seeing a parallel erosion of presidential authority: the steady drip-drip of casualty figures from Vietnam that proved the undoing of Lyndon Johnson's presidency in 1968, or the corrosive effect of the Iran hostage crisis on Jimmy Carter 12 years later.

We have now witnessed four similar killings of Western civilians in the conflicts unleashed by the attacks of 11 September 2001, starting with Daniel Pearl in Pakistan in January 2002 and including the Italian Fabrizio Quattrocchi in Iraq in April. Even in our jaded, news-saturated age there is something about these cases that bespeaks almost bottomless horror, in a way that the deaths of more than 800 US servicemen in Iraq or the violence and death visited upon thousands of Iraqi civilians have not.

The fact that the images of ritual slaughter have been posted on the internet has only made the brutality more vivid, more palpable - even to those who have not had the stomach or the inclination to watch. This is a propaganda war, fought with images as much as with guns and knives.

With each new beheading, the political mood has shifted. When the Wall Street Journal reporter Daniel Pearl was abducted in Karachi two-and-a-half years ago, it gave rise to a sense of national, even international solidarity. There was nothing divisive or controversial about the mourning that greeted news of his death. Indeed, his family has gone on to set up a foundation in his name to promote cross-cultural understanding that enjoys universal admiration.

The case of Nicholas Berg, the 26-year-old from Pennsylvania abducted and killed in Iraq just last month, was very different. There was the question of how exactly he had come to grief, with his family alleging he had been in US custody and that the FBI somehow put him in the path of danger on his release. And there was the anger of his father, Michael Berg, who said unequivocally: "My son died for the sins of George Bush and Donald Rumsfeld."

Mr Berg Snr was at an anti-war demonstration in Washington two weeks ago in which he continued to denounce the administration for its "callous behaviour" which, he said, had "in effect tied him [his son] to the track until it was no longer possible to escape that speeding hate train".

It would be wrong to believe that the rest of the United States shares Michael Berg's outlook. Rather, his anger has underscored the deep polarisation in American politics between those who have come to loathe the Bush administration and those determined to defend its every action. And it remains to be seen whether Mr Johnson's death provokes anger against the administration or rather cries for revenge against his butchers.

Still, the overall mood is slipping away from the President. Two recent polls show that a majority believe the war against Saddam Hussein was not worth it. The Abu Ghraib torture scandal remains incendiary. And the recent traumatic events in Saudi Arabia - the siege of a residential compound in the oil town of al-Khobar last month, the shootings of Americans and other Westerners, and now the grisly fate of Mr Johnson - have raised anxious questions about the direction of US foreign policy and its ostensible goal of diminishing the terrorist threat.

Yesterday, a Washington Post article was headlined: "Is al-Qa'ida winning in Saudi Arabia?" It was just such questions about America's enemies that led President Johnson to his "Cronkite moment" in 1968 - his realisation that he could no longer count on the support of the country's favourite television news anchor, Walter Cronkite, and that he had therefore lost the sympathy of the electorate as a whole.