Maarab, Lebanon

This year marks the 10th anniversary of Lebanon’s Cedar Revolution. On Valentine’s Day, 2005, Hezbollah operatives assassinated Rafik Hariri, a reformist former prime minister and an opponent of Syrian dictator Bashar Assad. More than a million Lebanese, Muslims and Christians alike poured into the streets to demand the withdrawal of a Syrian military force that had occupied the country since the end of the civil war in 1990. France and the U.S. gave their backing to the protesters, and the hated Syrians decamped for Damascus on April 30.

The Cedar Revolution exploded just as the Internet was beginning to transform how mass movements communicate with their supporters and with the outside world, and the Lebanese provided a template for the pro-democracy uprisings that would rock the region in subsequent years. This tiny nation of 4.5 million gave birth to the Middle East democratic awakening.

Today, democratic development in the world’s least-free region has stalled. Iran’s Green Revolution erupted in 2009 while the Obama administration was bent on rapprochement with Tehran and was quickly extinguished. Save for Tunisia, the Arab Spring has everywhere yielded chaos, repression and reaction. Four Arab states—Libya, Iraq, Yemen and Syria—are in various stages of disintegration.

And Lebanon is once more hostage to outside actors, mainly Iran and its proxies. “Hezbollah has a kind of veto power on the political life of Lebanon,” says Samir Geagea, the leader of the Lebanese Forces, a Christian militia turned political party, and a pillar of the anti-Hezbollah March 14 Alliance that grew out of the Cedar Revolution. “Not everything that Hezbollah wants will go on, but everything that Hezbollah wants to veto is vetoed.”

For Mr. Geagea, the Cedar Revolution meant freedom—literally. After the civil war, he was one of a very few national leaders to reject Syria’s domination of the country. For this he was tried in a proceeding widely criticized by international-rights bodies, and in 1994 he became the only militia leader imprisoned for his actions during a conflict in which no faction had clean hands. He spent the next 11 years in a tiny cell three floors beneath the Defense Ministry.

The Lebanese parliament granted Mr. Geagea amnesty in 2005. Today he lives in a heavily guarded compound in the mountains north of Beirut. Not far is a replica of the basement prison where he spent more than a decade, including the Syrian torture device—a ceiling chain used to suspend and beat victims—situated just outside his cell. In 2012 he survived an assassination attempt by sharpshooters firing from the hills surrounding his compound.

Asked who was behind the attack, one of Mr. Geagea’s aides winks and says, “We don’t know.” Since the Cedar Revolution, there have been at least 20 assassinations or assassination attempts targeting the leaders of the anti-Syria, anti-Hezbollah, anti-Iran March 14 Alliance, as well as officials of the Lebanese state.

It was through such means that the pro-Iran camp gained the political veto it wields today. Under Lebanon’s tri-sectarian constitution, the speaker of the Parliament is a Shiite, the prime minister a Sunni and the president a Christian. Mr. Geagea has declared his candidacy for the presidency, but he thinks Hezbollah will block the democratic process as long as “regional realities” suit it.

That’s shorthand for the sectarian conflict that has followed in the wake of America’s departure from the Middle East. “Why is Obama doing this to us?” I was asked repeatedly at a gathering of pro-March 14 intellectuals and business leaders in Beirut. Here, the Obama administration’s outreach to Iran’s mullahs, and talks that will almost certainly transform Iran into a nuclear-threshold state, are now seen as the expression of a long-standing American policy to empower the Islamic Republic at the expense of the Arabs.

If there has been a silver lining for the Arabs, it is that their leaders are now taking more responsibility for their own security. Exhibit A is the recent Saudi-led operation to push back the Houthis, Iran’s Hezbollah-style proxies in Yemen. Notably, the Saudi successes have coincided with the opposition making fresh gains on the ground in Syria. In an interview published Tuesday, Hezbollah leader Hassan Nasrallah declared that the collapse of the Assad regime would sound the death knell for his own group and the entire Iranian-led axis of “resistance.”

For Mr. Geagea, who has spent his political life fighting the Assads, with and without arms, that prospect isn’t far off. “You can kill a quarter of a million people and hold on—hold on to what?” he says. “Assad will fall, if not today then tomorrow.” Similar predictions, it bears reminding, were made a decade ago.

Mr. Ahmari is a Journal editorial-page writer based in London.