Ambulances are surrounded by people at the entrance of the American University of Beirut Medical Center, on September 17, after explosions occurred in several Hezbollah strongholds in Lebanon.

Families in Lebanon may have lived next door to a member of Hezbollah for years without ever knowing that their neighbor was a member of the Iran-backed militant group, the country’s most powerful military and political organization.

But one afternoon, that leak sprang when thousands of pagers used by members exploded in people’s hands and belts.

The operation succeeded in temporarily breaking one of Hezbollah’s most strategic assets: secrecy.

The group’s guerrilla tactics, developed during Israel’s 18-year occupation of southern Lebanon, have made them an elusive enemy.

The practice of hiding in the shadows continues today, even as Hezbollah has become one of the two main parties representing the Shiite community, Lebanon’s largest religious bloc. Today, there are 13 elected Hezbollah lawmakers in parliament, and posters celebrating Hezbollah martyrs can be seen in many Shiite communities.

During my reporting in the country, I occasionally encountered members of Hezbollah’s security detail. They were always men in plain clothes and sometimes carrying walkie-talkies. They asked to check my documents and on several occasions ordered me to leave an area they said was “sensitive.”

Their undercover presence was a stark contrast to the camouflage-clad Lebanese army soldiers who drive Humvees and guard checkpoints while carrying assault rifles.

Tuesday’s attack was “a huge blow” to Hezbollah, wrote Amal Saad, an expert on Islamist movements.

But in one fell swoop, Israel wiped out that advantage, she said, when thousands of those beepers were converted into deadly weapons.

It is unclear whether all of the people carrying the explosive beepers were Hezbollah fighters, as the group’s “state within a state” also supports hospitals, schools and other charities. Some may also have fallen into the hands of ordinary people unaffiliated with Hezbollah.

While Hezbollah has vowed to take revenge on its southern neighbor, one thing is certain: the country is likely trying to hide the extent of the damage, partly to avoid sharing more secrets with its enemy.