Lebanon's volatile border witnessed the most serious bout of violence in four years Tuesday when clashes between Lebanese and Israeli soldiers left at least four people dead.

While tensions have been running high between Lebanon and Israel amid feverish speculation of another war between Israel and Lebanon's militant Shiite Hezbollah, analysts and security sources say that the cross-border clash is probably an isolated incident.

"This is a controllable situation as long as it stays between the armies of two states," says Timur Goksel, a university lecturer in Beirut and former long-serving official with the United Nations peacekeeping force in south Lebanon, known as UNIFIL.

How the clash broke out

The fighting broke out around noon when Israeli troops attempted to cut down a tree on the border near the Lebanese village of Addaisseh that apparently was obscuring the view from a military observation post. It remains unclear who fired first – both Lebanon and Israel blamed each other for triggering the fighting.

At least two Lebanese soldiers were killed and another two wounded when an Israeli tank shell struck their checkpoint beside the border. A Lebanese correspondent for Lebanon's Al-Akhbar newspaper was reportedly killed and another journalist for the Hezbollah-run Al-Manar television was wounded.

Israel said that an Israeli lieutenant colonel was killed and another Israeli soldier "severely wounded." Security sources in Lebanon said that the occurrence of Israeli casualties explained the unusual intensity of the fighting.

"This is the most serious incident since 2006 and these are the first fatalities as a result of the hostilities since 2006," says Milos Strugar, UNIFIL's senior political adviser.

UNIFIL requested a cease-fire

Hezbollah went on high alert in Beirut and south Lebanon, but stayed out of the fighting in Addaisseh, effectively ensuring that the clashes would be contained.

Intermittent fighting continued into the afternoon, ending only when UNIFIL requested a cease-fire to allow Brig. Gen. Santi Bonfanti, UNIFIL's deputy commander, to fly in a helicopter to the scene of the clashes.

"It was difficult for both sides to be the first to back down, so we provided a pretext by requesting the cease-fire," a UNIFIL officer says. Lebanese President Michel Suleiman and Prime Minister Rafik Hariri condemned Israel for attacking Lebanese troops.

"The international community bear their responsibilities and pressure Israel to stop its aggression," Hariri said in a statement.

The Israeli foreign ministry held Lebanon responsible for "this grave incident" and warned of the consequences "in the event that disturbances of this kind continue."

Both sides preparing for fresh war

The deadly clash underlined the volatility of the Lebanon-Israel border, even though it has enjoyed its longest period of calm in four decades. The devastating 2006 war ended inconclusively and expectations of a renewed conflict between Hezbollah and Israel have intensified with each passing year.

Both sides are preparing for another encounter – Hezbollah has recruited and trained thousands more fighters and amassed a large arsenal. The Israelis have retrained their army and brought in new defensive systems to protect against Hezbollah’s rockets and missiles.

But analysts say that while another war is a strong possibility, neither side appears eager to embark upon a conflict that many expect would be even more destructive than the last one.