What seems at first like a relatively minor skirmish between the Lebanese and Israeli armies - in a border that has been unstable for at least 40 years - will have major political significance for Lebanon and the region.
For the Lebanese Armed Forces this was like a baptism of fire. The army had not been in control of the southern border since the late 1960s, and only deployed there recently as a result of UNSC resolution 1701 in the aftermath of the 2006 Israel-Hizbullah war.
Since 1948, the Lebanese army has kept out of the major Arab-Israeli wars and although Israel has invaded and occupied the country several times since the late 1970's, the army has largely kept to its barracks, maintaining itself as a national institution but keeping out of the fighting.
This has not been without cost. The main division in Lebanon since independence has been over its regional role and whether it should participate actively and militarily in support of Arab causes. Lebanon's 'isolationism' has often been opposed and led to political crises, such as the fifteen year Civil War which was triggered, in part, by disagreement over support for Palestinian resistance using Lebanon as a base to attack Israel.
In more recent times, this sort of division translates regionally into two camps: one that supports negotiation with Israel led by Saudi Arabia and Egypt and allied to the United States with former Prime Minister Rafic Hariri and now his son Saad Hariri representing this stance in Lebanon; and the other calling for armed resistance and confrontation led by Syria with Hizballah and Hamas in alliance with Iran.
Last month King Abdallah of Saudi Arabia accompanied by President Bashar el Asad of Syria and followed by Sheikh Hamad bin Khalifah al Thani of Qatar, visited Lebanon to avert the repercussions of a possible indictment of Hizballah members by the Special Tribunal for Lebanon in connection with the assassination of Rafic Hariri in 2005. It is feared that a indictment of Hizballah would reignite the conflict in Lebanon and threaten stability in the region, in which the Saudi monarch has a large stake. The assassination of Hariri in 2005 exacerbated Arab divisions and this visit was part of the move for Arab reconciliation led by the Saudi monarch.
The border incident with the Lebanese Army comes with a mixed message - it partly focuses minds on the conflict with Israel and away from internal Arab divisions, it also symbolically asserts the sovereignty of the Lebanese state on the border hitherto controlled mainly by Hizballah. Together with its responsibility of stopping any Israeli incursion, it marks a quantum leap in Lebanese policy in which the Lebanese state itself - with the army - have moved firmly towards the confrontation camp.
One of the lasting images of the 2006 Israel-Hizballah war was that of Lebanese army officers offering tea to Israeli army officers in the southern Lebanese village of Marjeyoun while coordinating the evacuation of civilians from the area. Almost exactly four years later, they had their first military confrontation with the Israeli army because it was trying to trim a tree.
Listen to Nadim discuss this on BBC R4's The Today Programme >>