Hezbollah, the Shiite Muslim group that captured two Israeli soldiers earlier this week, has long been one of the deadliest militant organizations in the Middle East and one of Israel's most potent foes.
The group was born in 1982 in reaction to an Israeli invasion of Lebanon that reached Beirut, the Lebanese capital, but the organization now has tentacles that experts say extend well beyond its home base in Lebanon's predominantly Shiite south. Operating freely in southern Lebanon, Hezbollah, "The Party of God," receives financial and material aid from Iran, with many of the weapons being transferred through Syria.
"It's a serious force both in political and militant terms," said David Schenker, senior fellow in Arab politics at the Washington Institute for Near East studies. "They not only have the money and the weapons, they have a great amount of respect among a lot of Lebanese people."
It has become a significant, mainstream political force, with its members holding seats in Lebanon's elected parliament and two Cabinet ministries - a status achieved even as the group maintained an armed militia.
In that way, its military and political wings operate in tandem, as is also believed to be the case with Hamas - the militant Islamic group that has become the dominant political force in the Gaza Strip - and as the Irish Republican Army and Sinn Fein once did.
Hezbollah's political experimentation and military ascendency came last year, after the assassination of Lebanon's ex-prime minister, Rafik Hariri. Syria was held responsible and Lebanese protesters, fed up with interference in their country, staged huge protests. Syrian soldiers ended their decades-long occupation and returned home.
With the Syrian army gone, Hezbollah became the most powerful military force in the country. And sensing a power vacuum and a new mood favorable to democracy, Hezbollah ran candidates.
Lebanon's prime minister leads an anti-Syrian alliance but its president, Emile Lahoud, and other important government figures, are still seen as beholden to Syria and, by extension, Hezbollah.
Its political success has come much the way the Sunni Muslim group Hamas won power in the Palestinian territories: by providing goods and services more efficiently than the current government.
Its stated goal is to create a Muslim fundamentalist state modeled on Iran, but it has walked a rhetorical fine line in Lebanon, a country that has long been a refuge for the region's persecuted minorities, including Christians, Sunni Muslims, Shia Muslims, Druze, Palestinians and others.
Hezbollah has about 13,000 short-range rockets capable of reaching Israel, said Michael Herzog, a brigadier general with the Israeli army and now a visiting military fellow at The Washington Institute.
"This has been a root cause of the tensions with Israel," he said. "Israel let them build that force because it didn't want to open a second front. Now, it seems there is no choice."
In 2000, Hezbollah kidnapped three Israeli soldiers. Four years later they were returned, dead, in exchange for hundreds of Palestinian and Lebanese prisoners freed by Israel.
The United States holds the group responsible for the suicide truck bombing in 1983 that killed more than 200 U.S. Marines in Beirut, and for attacks on Jewish targets in Argentina in the 1990s that killed more than 120.
"The question has long been whether Hezbollah can make the transition from militancy to politics and governance," said Gideon Rose, a former National Security Council official in the Clinton administration and now managing editor of Foreign Affairs for the Council on Foreign Relations.
The capture of the soldiers, he said, may energize hawks in Israel.
"That does not necessarily mean full-scale war between Hezbollah and Israel," Rose said. "But it's a major step in the wrong direction."