Tony Blair's hopes that this was to be Africa's week in the world media and the beginning of a second chance for the impoverished continent were blasted to bits in London early yesterday by terror squads with other priorities.

This much was clear immediately in the flash of the explosions in the London Underground: Cowardly killers such as these care not a whit about raising Africans out of poverty, fighting AIDS and climate change, or addressing any of the other worthy topics on the Group of Eight agenda constructed by the British prime minister. If Africa is buried under the collateral damage of these blasts, so be it; this is their attitude.

The true motives of terrorists are rarely known with certainty. Their communiques glorifying criminality and blood lust in the name of politics or religion, or some perverse mixture of the two, are unreliable guides. These are people, if the word applies, who kill because they can.

They kill to break the will of their opponents, to purchase a ticket to paradise, to be paid in coin or a sick kind of prestige. The idea that they are punishing Blair -- for whatever reason -- by driving his efforts to double aid to Africa's poor off the world's front pages and television screens invites contempt and even derision.

The protesters and rock stars who compete with the politicians for the oxygen of publicity at the annual summits of industrial democracies also stand eclipsed. Their complaints that Blair, President Bush, Jacques Chirac, Junichiro Koizumi and the others are not compassionate or effective enough in sending aid to Africa can only seem puny when juxtaposed with the murderous evil unleashed on workers heading to their jobs in London's rush hour yesterday.

Blair responded to the violence with appropriate calm and determination. He is not a man who will be cowed or deflected from his course by his enemies, or who will let emotion dictate his strategy. The nominal leadership of the G-8 that was his this year by custom has been transformed by his citizens' blood into a real authority over this group of presidents and prime ministers.

They have now been challenged frontally and as a group by the timing of the attack on their host nation. They must decide whether they will respond as a group -- by intensifying concrete contributions to fighting global terrorism -- or as separate nations seeking separate truces with al Qaeda, its offshoots and ilk who have left these leaders no place to hide.

Every G-8 nation has active-duty military units in Afghanistan or Iraq, with the exception of Russia, which fights its own campaign against Chechen terrorism. Such nations are "crusader[s]," as the initial assertion of responsibility for the London attacks by an Islamic fundamentalist group termed them, and therefore targets.

But the bombers unintentionally have emphasized that they represent nothing but a malignant, backward view of humanity and history by subordinating the needs of starving, ill Africans to their political agenda.

Blair's commitment to Africa is a central part of a belief I have heard him express on a number of occasions: International political responsibility must accompany economic globalization as national boundaries become more porous to goods, ideas and people.

He has backed humanitarian intervention to protect vulnerable populations in Kosovo and elsewhere. Blair set the focus of the G-8 meeting at Gleneagles, Scotland, on providing massive new aid to a continent where per capita income, life expectancy and chances to escape extreme poverty have declined markedly over the past two decades.

Are there second acts in the lives of continents? Blair's energetic efforts seemed to raise that question. Africa emerged from colonialism almost a half-century ago with bright political promise. Independence would drop the fruits of nationhood into the laps of the people by giving them control over their destinies, it was broadly assumed, and promised.

The political illusions soon evaporated as economies stagnated, dictators took power, armies mutinied and civil wars set tribes against each other. The continent's few bright spots -- particularly South Africa -- were lost in a spreading despair.

Blair's proposals were never going to solve all of Africa's problems. His greatest accomplishment at Gleneagles might have been to get people to look at Africa differently -- to put aside the hopelessness and despair -- and rekindle international engagement there.

Hope is not permitted to exist for others by the killers of London, Madrid, New York, Northern Virginia, Baghdad, Kabul and elsewhere. They traffic in despair, resignation and surrender. The G-8 leaders have said the terrorists will not prevail. It is up to those leaders to show that they mean those words.