When Meir Dagan was appointed head of the Mossad eight years ago, Saddam Hussein ruled Iraq, Yasser Arafat was imprisoned in Palestinian Authority headquarters in Ramallah and Mahmoud Ahmadinejad, today Iran's president, was studying engineering at Iran University of Science and Technology. Back then, Israel was fighting a wave of suicide bombings, the economy was on the verge of collapse and national morale was at a nadir.

Ariel Sharon, who was prime minister at the time and knew Dagan from the army, placed him at the head of the secret service for the purpose of restoring its willingness to play offense. Sharon reportedly said that "Meir's expertise is separating Arab heads from their bodies."

Throughout his tenure, Dagan stood out for his willingness to take risks and his ability to convince his political overseers to trust him. That is what Sharon wanted. And the principal mission he assigned to Dagan was stopping Iran's nuclear program.

But Dagan thought this was mission impossible. "Iran has decided to go nuclear ... and nothing will stop it," an American diplomatic cable published by WikiLeaks quoted him as telling a U.S. senator in 2005.

The leaked cables reveal that the Israeli-Iranian conflict is about more than the nuclear issue. It is a sweeping ideological conflict. And history teaches that such conflicts end only when one side has been knocked out. That was the case in the confrontations between Stalin and Hitler, between American capitalism and Soviet communism, and between Zionism and Nasserism.

The Iranian president openly declares that the "Zionist regime" will fall. Israeli leaders are more cautious in public, but in off-the-record conversations, they sound like Ahmadinejad in reverse.

At a meeting in the summer of 2007, Dagan presented the Americans with a comprehensive strategy for toppling the Iranian regime. Israel and the United States, he said, "could change the ruling regime in Iran ... We could also get them to delay their nuclear project. Iran could become a normal state."

Dagan emerges from the cable as an advocate of the strategy of using minimal military force but lots of tricks to wear down the enemy. He proposed fomenting unrest among Iranian students and minorities and exploiting Iran's economic distress to undermine the regime and create rifts within it. He also suggested unspecified "covert measures."

Dagan reached the peak of his influence during Ehud Olmert's term as prime minister. The Mossad chief's assessments of the situation during the Second Lebanon War proved correct; thus even though his suggestions were rejected, Olmert learned to trust him.

According to foreign sources, Dagan brought Olmert incriminating information about a Syrian nuclear facility that led to its being destroyed by aerial bombing. A few months later, senior Hezbollah operative Imad Mughniyeh was assassinated in Damascus. These operations and others like them revived the national morale, and there are those who claim they also contributed to delaying Iran's nuclear program by several years, in addition to imposing technical difficulties and growing international pressure.

But however daring they were, these covert operations did not alter the region's strategic balance. Iran continued to grow stronger, despite the difficulties. The strategy of minimal military force brought Israel economic growth and quiet on the security front, and also brought it closer to the moderate Arab states, which fear Iran as well. But it did not suffice to bring victory in the larger conflict.

Benjamin Netanyahu's return to power, along with that of Ehud Barak, heralded the waning of Dagan's power. According to the WikiLeaks cables, Netanyahu and Barak believe that small operations are not enough, and that defeating Iran will require the use of military force. After all, the Syrian nuclear facility was destroyed by aerial bombing, not by surgical assassinations or diplomatic pressure.

The so-called Yishai-Leaks documents, which the Interior Ministry released after the Carmel fire in an effort to clear Interior Minister Eli Yishai of blame for the fire services' lack of preparedness, show that Israel had prepared for a "security escalation" this past summer. But Dagan, judging by his warnings during the Second Lebanon War, continued to demur, until he was finally pushed out.

The assassination of Mahmoud al-Mabhouh in Dubai, which has been attributed to the Mossad, cast a shadow over Dagan's final year in office. Since then, the Mossad has also allegedly been behind the Stuxnet worm, which damaged the computers running Iran's nuclear program, and last week's assassinations, which killed one senior Iranian nuclear scientist and wounded another.

Assuming that Dagan was indeed involved in the latter, this operation, in the heart of Tehran, proves that the Mossad did not lose its nerve, or its abilities, after Dubai. It was an honorable conclusion to Dagan's lengthy tenure, even if his principal mission was not accomplished.