Benazir Bhutto's assassination in Pakistan is likely to prompt calls for a wholesale review of U.S. policy toward a country crucial to regional stability and the continuing war on terrorism. Such a review is overdue, considering the minimal results from the $10 billion in U.S. aid funneled to President Pervez Musharraf's government since 2001.

President Bush blames "murderous extremists" for the attack. But Musharraf shares responsibility for failing to provide adequate security as Bhutto campaigned ahead of January's national elections. He led a tepid investigation into an Oct. 18 bomb attack on her motorcade, in which 140 were killed. His unenthusiastic attitude toward democracy raises serious doubts about his leadership, as suggested by former Prime Minister Nawaz Sharif's call for his immediate resignation.

Although a review of this relationship is in order, Washington should not make any sudden or drastic moves. Few countries are as potentially volatile and dangerous as Pakistan, and the Bush administration must move cautiously. A tiny tweak in U.S. policy can have cascading enormous ripple effects.

Pakistan is armed with dozens of nuclear weapons. Its military and intelligence services contain elements sympathetic to Islamist extremists. Potentially hostile forces abound on its borders while al-Qaida and the Taliban maintain encampments inside Pakistan.

It seems easy to blame terrorists such as al-Qaida for the assassination, and it is worth noting that Musharraf has survived multiple attempts on his life. But we also cannot ignore the instability provoked by Musharraf himself.

He recently blocked democratization efforts, suspended the constitution, jailed his political opponents, ransacked the judiciary, opposed Bhutto's return from exile and refused to relinquish his military title of general and army commander.

Since Musharraf's 1999 overthrow of a democratically elected government, Pakistan has been under military domination. To justify his power grab, Musharraf blamed corruption by Sharif and Bhutto during her two terms as prime minister. But Transparency International, a group that monitors corruption and governmental openness, says corruption appears to have worsened during his rule.

Musharraf's gregarious and soft-spoken demeanor masks the darker side of his personality. He has been ruthless in his quest to remain in power, and only a careful application of pressure from Washington persuaded him to step down as army commander a month ago.

With riots now spreading around the country, Musharraf will no doubt be tempted to declare emergency rule or delay the elections. The Bush administration should oppose any such action. To allow any further postponement of the elections is to reward Musharraf for mismanaging U.S. aid and squandering the trust of his people.

The best way to restore calm is to ensure that neither terrorists nor Musharraf succeed in derailing the democratic process.