PHILADELPHIA -- The scenes were grisly.
The U.S.-educated Benazir Bhutto, first female prime minister of Pakistan, newly returned from years in exile, was riding in a caravan through Karachi streets surrounded by tens of thousands of adoring supporters. Then came the explosions. Fire and body parts, most likely the work of al-Qaida, perhaps with aid from Taliban allies.
Ms. Bhutto survived; more than 130 died. But the blasts were a wake-up call for her, Pakistan's President Pervez Musharraf, and us.
While Americans are focused on the Iraq war and a possible Iran war, the greatest danger to us lies within Pakistan. So says the U.S. government's latest National Intelligence Estimate on "The Terrorist Threat to the U.S. Homeland." It concludes that "the most serious terrorist threat to the homeland is and will remain" al-Qaida, which has established a haven in the tribal areas of Pakistan.
America's ally, General Musharraf, has failed to prevent al-Qaida and the Afghan Taliban from establishing a base in mountainous regions along the border with Afghanistan. His army has proved ineffective at fighting insurgents.
Ms. Bhutto charges that Pakistan's intelligence agencies are still penetrated by an old guard that helped train Afghan militants to fight the Soviet Union in the 1980s - and is still sympathetic to jihadis. This old guard is also said to be helping homegrown Islamic radicals who are fighting India over Kashmir.
On Friday, Ms. Bhutto accused "people in positions of power" of providing logistical support for extremists who tried to kill her. Of course, Pakistan's government denies this. But the facts show Mr. Musharraf has been unwilling or unable to crush extremists at home who have tried to kill him, too.
The attempted murder of Ms. Bhutto reflects the growing ability of Pakistani militants to destabilize a country that (unlike Iran) already has nuclear weapons. Pakistan is also a nation whose leading nuclear scientist, Abdul Qadeer Khan, was able for years to sell nuclear technology to countries such as Libya, Iran and North Korea - supposedly without his government's knowledge. The West's nightmare scenario would be the illicit transfer of Pakistani technology to al-Qaida or other fanatic Islamists.
Yet, for all its horror, the Karachi outrage could finally generate the necessary momentum to confront this threat.
The Karachi bombs "may be what's needed to make the Pakistani population unite against the terrorists," says Husain Haqqani, director of the Center for International Relations at Boston University, and an adviser to three past Pakistani prime ministers, including Ms. Bhutto.
The bombings may rally public support for Ms. Bhutto. She has called publicly for ridding Pakistan of al-Qaida and other extremists, and hopes to become prime minister again if her party wins parliamentary elections, scheduled before mid-January.
Ms. Bhutto faces legal and political hurdles. Mr. Musharraf, who has smothered civilian rule, was recently elected to a second term by parliament under questionable circumstances. No one knows if he will now shed his military uniform, as he's pledged, or if he'll permit fair elections. The biggest question is whether the recent deal he made with Ms. Bhutto to share power will hold up after the murder attempt.
But a popularly elected prime minister would have the legitimacy to take on terrorists - legitimacy Mr. Musharraf lacks - if the army and the intelligence services back her. Mr. Haqqani hopes the bombings will convince Mr. Musharraf that such legitimacy is crucial. He also hopes Mr. Musharraf will now see the need to "purge the government and intelligence services of hard-liners who supported jihadis."
Many question Ms. Bhutto's ability to lead such a battle. Her two past prime ministerships were disappointing; she was dogged by corruption charges. Her behind-the-scenes bargaining with Mr. Musharraf may diminish some of her support. But she has made a strong public case for tougher action against al-Qaida and the Taliban.
"We abhor handing over ... part of the country to foreigners, Afghan Taliban, Arabs, Chechens," she said in August. "We must take that territory back. The more you give them, the more they want."
Last week's attack on Ms. Bhutto's life may convince many Pakistanis that it's time to crack down on militants - and that she has the guts to do it. Perhaps the bombs (and the White House) can persuade Mr. Musharraf to join forces with her against extremists who threaten us all.
Trudy Rubin is a columnist for The Philadelphia Inquirer. Her column appears Tuesdays in The Sun. Her e-mail is email@example.com.
Clarence Page's column will return Friday.