Do rockets in Israel indicate Al Qaeda presence in Lebanon?

That's one theory. The distance the rockets were able to travel indicated use of a long-range weapon that only a local Al Qaeda-linked group is believed to have.

At least three rockets were fired Thursday from south Lebanon into northern Israel, causing no casualties or damage.

The lack of casualties in Israel and the military's decision to refrain from firing artillery rounds at the source of rocket fire – a routine response to similar attacks in the past – suggests that Israel is not interested in escalating the situation along its once-volatile border with Lebanon.

One of the rockets was reportedly intercepted by Israel's Iron Dome missile defense system between the coastal town of Nahariyah in northern Israel and Acre further south. Initial reports said that two other rockets exploded near Nahariyah and one possibly fell near the Lebanese border village of Alma Shaab. However, an Israeli army spokesman said that no other rockets struck Israeli territory, suggesting they might have fallen into the sea. 

The Lebanese army discovered the launch site in orange orchards between Batouliye village and the Rashidiyah Palestinian refugee camp, just south of the coastal town of Tyre. Although the exact type of rocket fired Thursday was not immediately known, in the past militants have employed 122-millimeter and 107-mm Katyusha rockets with ranges of about 12 miles and seven miles, respectively, to target Israel.

But the distance from the launch site in Lebanon to the reported location of the Iron Dome interception is closer to 20 miles, suggesting that the rockets, or at least one of them, may have been of the extended-range version. If confirmed, the only group in Lebanon believed to be in possession of the extended-range 122-mm Katyushas outside the Lebanese militant Shiite group Hezbollah is the Al Qaeda-linked Abdullah al-Azzam Brigades, according to a security source in Lebanon. The Abdullah al-Azzam Brigades claimed responsibility for a similar rocket attack in Israel in September 2009. 

There was no immediate claim of responsibility for today's rocket attack, the first in nine months. The Israeli army said it was a “one-time incident” and blamed the attack on the “international Jihad movement,” a reference of Al Qaeda-inspired groups.

The Lebanon-Israel border has enjoyed a seven-year period of relative calm since the month-long war between Israel and Hezbollah in 2006. The last time rockets fired from Lebanon struck Israel was in November 2011. Since then, there have been three attempted rocket launches from south Lebanon, one in December 2011 and two in November 2012, but none of the rockets made it across the border.

Those attacks were generally amateurish, with the rockets fired by a timing mechanism from makeshift launch pads of wooden planks.

Sunni jihadist militants are known to live in the Rashidiyah refugee camp and the camp’s proximity to the launch site make them the leading suspects, according to a Lebanese security source.

Lebanon is extremely tense due to Sunni-Shiite tensions fomented by Syria’s bloody civil war. Hezbollah is deeply involved in the war, dispatching thousands of fighters to assist President Bashar al-Assad's regime, enraging the predominantly Sunni Syrian opposition. Hezbollah has come under attack in Lebanon on numerous occasions from suspected Syrian rebel groups and their Lebanese Sunni supporters. 

Last week, a car bomb blast in the southern suburbs of Beirut killed 30 people, the deadliest toll since the 1975-90 civil war. Since then Hezbollah has imposed tight security restrictions in its southern Beirut stronghold to prevent widely-expected further attacks. The rocket attack into Israel is likely an attempt by Hezbollah’s Sunni opponents to destabilize the border area, potentially to implicate the Shiite group, which has previously launched rocket attacks at Israel from southern Lebanon.

Despite Hezbollah’s involvement in Syria, it keeps a close eye on its primary enemy, Israel. On Aug. 7, four Israeli soldiers from the elite Golani regiment were wounded during an unusual incursion into Lebanese territory near the long-abandoned farmstead of Labboune on the border. The soldiers were part of a 12-man team that were on an as yet undisclosed mission when they were struck by a roadside bomb in dense brush 440 yards north of the border fence.

Sheikh Hassan Nasrallah, Hezbollah's leader, subsequently claimed responsibility for the attack, saying that his party had obtained prior intelligence of the impending raid and had set up defensive bombs. 

"We will confront any entry by Israelis into Lebanese territory of which we know," he said. "We will cut off the feet of those entering our land."