Saad Hariri, who resigned Saturday as Prime Minister of Lebanon, always faced a no-win situation trying to serve in that role. His departure heralds the latest ratcheting up of tensions between Saudi Arabia and Iran playing out across the region, with significant implications for Israel.

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Hariri is a good man, but not a natural political leader. His role as the leader of Lebanon’s Sunni bloc was thrust upon him by the assassination of his father, Prime Minister Rafik Hariri, in 2005.

During his first term as prime minister, from 2009 to 2011, Saad chose, by design, to operate in his father’s imposing shadow. When I visited his compound in Beirut, I was struck not only by the opulent wealth and suffocating security arrangements, but by the extreme deference to Rafik’s memory. In the salon where he received guests, Saad sat in the second chair on the Lebanese side. The first was reserved for a black ribbon-draped portrait of his father.

But there was another force that thrust him into that role: his Saudi patrons. Saudi Arabia had long backed the Sunnis in Lebanon’s multi-sectarian political system and during the civil war. But they also provided a base and financial backing for the Hariri business empire. Hariri could not move right or left without Saudi support, nor could he rebuff their orders that he return to Lebanon as prime minister.

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Open gallery view Saad Hariri, Lebanon's now former prime minister, at a joint press conference with U.S. President Donald Trump, at the White House in Washington, D.C. July 25, 2017 Credit: Zach Gibson/Bloomberg

During Hariri’s first term, he faced no end of headaches: Hezbollah-affiliated ministers in the cabinet who could bring down his government at any time; the unfinished business of the Special Tribunal investigating his father’s murder; and the taunts and bullying of Hezbollah’s ally, Bashar Assad in Syria. The certain knowledge that Hezbollah, backed by Assad, were the culprits in his father’s killing must have made each day a special kind of torture.

Those ressures all reflected Iran’s ongoing attempt to retain its influence in Lebanon, and recover the ground they had lost when the March 14 popular uprising following Hariri senior's assassination resulted in the withdrawal of Syrian troops after 30 years.

With sustained support from Saudi Arabia and the United States, Saad Hariri withstood these pressures for a time. But Saudi support wavered in 2010, when Prince Abdulaziz, the son of then-King Abdallah, pursued a rapprochement with Assad. When Hariri refused to play along, Hezbollah withdrew its ministers from his government, bringing it down in humiliating fashion while Hariri met with President Barack Obama in Washington in January 2011.

As I watched his face across the Oval Office that day, Hariri seemed almost relieved.

Knowing that history, I was frankly surprised when he returned to the premiership late last year, following a protracted government stalemate, so bad that even the Lebanese trash was not being collected. The logjam was only broken when Michel Aoun, a Christian ally of Hezbollah, ascended to the presidency.

Open gallery view Saudi Crown Prince Mohammed bin Salman (known as MBS) poses while meeting with Turkey's President Recep Tayyip Erdogan in Jiddah, Saudi Arabia. July, 23, 2017 Credit: /AP

Why would Hariri return under an even tougher set of circumstances than those that prevailed during his first term? Once again, because the Saudis made him an offer he couldn’t refuse.

But this was a new breed of Saudi rulers. King Abdallah had no love for Iran, whom he described as the head of the snake spreading poison throughout the Middle East. But he picked his spots for confronting his rivals, and cut his losses in Lebanon in 2011. His successor, King Salman bin Abdulaziz al-Saud, and his son Prince Mohammed bin Salman (MBS), seem determined to contest Iran from Yemen to Syria to Lebanon. Getting their man, Hariri, back to Beirut at least gave them a player on the field.

Hariri faced a truly impossible task. Hezbollah’s dominance of Lebanese politics has only increased. Despite continued U.S. support for the Lebanese Armed Forces, ostensibly a multi-confessional counterweight to the Shia forces, is has become increasingly clear that Hezbollah can intimidate, infiltrate, and when called upon, dominate them.

The winding down of the Syrian civil war made it even worse. As long as the fighting raged, Hezbollah’s priority was shoring up the Assad regime, which has facilitated the conveyance of Iranian weapons into Hezbollah’s hands. As Assad’s future has been assured, under Russian and Iranian sponsorship, Hezbollah fighters have been returning home to Lebanon, and their leadership has been able to refocus on internal Lebanese battles.

Open gallery view Rescue workers and soldiers stand around a massive crater after a Hezbollah bomb attack that killed former Prime Minister Rafik Hariri in Beirut, Lebanon. Feb. 14, 2005 Credit: /AP

Hariri has long known that as prime minister, he lived on borrowed time. At Hezbollah’s whim, at any moment, his father’s fate could become his own. It’s fair to say that the assassination attempt he alluded to in his resignation announcement represented a death threat he always faced. It was only a question of when Hezbollah would choose to operationalize it.

The bigger question is whether his resignation is a sign that the Saudis withdrew their support for him once again. At first blush, that would not seem consistent with King Salman and MBS’s overall desire to confront Iran’s proxies on every front.

But it is plausible that the Saudis are trying to create the context for a different means of contesting Iran in Lebanon: an Israeli-Hezbollah war.

With Assad clearly having survived the challenge posed by Saudi-backed rebels, the Saudi leadership may hope to move its confrontation with Iran from Syria to Lebanon. By pulling Hariri out of his office, they may hope to ensure that Hezbollah gets stuck with the blame and responsibility for Lebanon’s challenges, from caring for Syrian refugees to mopping up Al Qaida and ISIS affiliates.

Open gallery view Hezbollah leader Sheik Hassan Nasrallah delivers a video link message during Ashura, a 10-day ritual commemorating the death of Imam Hussein, in a southern suburb of Beirut, Lebanon. Sept. 30, 2017 Credit: Hassan Ammar/AP

That could, the Saudis may believe, lead Hezbollah to seek an accelerated confrontation with Israel as a means of unifying Lebanese support for their dominance. As indicated in a different context - this week’s arrests of Saudi princes in a putative corruption crackdown - King Salman and MBS have little patience to establish their desired order.

Israeli leaders have been preparing for the next war with Hezbollah since 2006. Iran’s increasing assertiveness across the region makes clear that, even more than the last war, it will be a fight to diminish the Iranian threat on Israel’s borders. Israel and Saudi Arabia are fully aligned in this regional struggle, and the Saudis cannot help but be impressed by Israel’s increasing assertiveness to strike at Iranian threats in Syria.

Israel will have to make its own decision when the time is right for that fight. When the moment of truth arrives, Israel’s allies, with the United States in the lead, should give it full backing. An act of Iranian or Hezbollah aggression may well be the spark, as their malign intentions are perfectly clear.

But Israeli leaders will want to take care not to find themselves backed into a premature confrontation by the maneuvers of their allies who sit in Riyadh.

Daniel B. Shapiro is Distinguished Visiting Fellow at the Institute for National Security Studies in Tel Aviv. He served as U.S. Ambassador to Israel, and Senior Director for the Middle East and North Africa at the National Security Council, during the Obama Administration. Twitter: @DanielBShapiro