That has not stopped it from amassing substantial political power inside Lebanon, according to author and journalist Thanassis Cambanis.

"They provide in a fair and efficient way, but Hezbollah is also authoritarian, power-hungry and militaristic," said Cambanis, who has reported extensively in the region for the Boston Globe and the New York Times. "They believe in a religious and pious society that embraces a fundamentalist Shia Islam. They believe in self sufficiency through war."

Iran and Syria support Hezbollah's ideology. Both countries have provided the group, which has a military wing, with financial backing and weapons for years. Hezbollah also makes millions through illegal businesses around the world, including global drug trafficking, the U.S. has charged.

Have there been widespread protests in Lebanon? Against what?

Protests have been more isolated. After al-Hassan's funeral Sunday, angry protesters clashed with security forces and rushed toward Mikati's office in central Beirut, calling for his dismissal. The mob hurled sticks, stones and flags. A smaller, peaceful demonstration continued later Sunday as government figures called for calm.

Most of the protesters are allied with Sunni coalitions that have long been sharply critical of the Lebanese government's perceived closeness with the Syrian regime, blaming Mitaki for not preventing Friday's deadly car bomb.

Why could Syria's problems become Lebanon's? They're two different countries, after all.

The major concern for Lebanon is that Syria's troubles will reopen the wounds of Lebanon's 15-year-long civil war, which ended in 1990.

Lebanon has always struggled to maintain a balance among its religious and ethnic sects, and the current tensions mirror those in Syria: In both countries, the Shiite and Alawite Muslim sects (al-Assad is an Alawite) tend to support the Syrian regime, while support is growing among Sunni Muslims for Syrian rebels.

The country also has a large Christian population, and both Sunni and Shiite groups have lobbied for Christian support during past conflicts.

Sunnis are in the majority in northern Lebanon, where they have clashed with a small but strong enclave of pro-al-Assad Alawites. The core of the Syrian president's support in Lebanon is in the southern part of the country.

The good news is that the war exhaustion factor is very high in Lebanon, Phillips explained. Beirut is still recovering from Israel's shelling of the city in 2006 during a 34-day conflict sparked by Hezbollah's kidnapping of Israeli troops near the Lebanese border, and many other wounds from the 1975-90 civil war have yet to heal.

"There's been an assumption for several years that the Lebanese people are fed up and exhausted with civil war," Phillips said. "The civil war there ended not because of any resolution but simply because people lost the will to keep fighting."