Senior Israel Defense Forces staff and defense establishment personnel are very concerned about the possibility of a serious incident on the Lebanese border in the near future.

Tensions with Hezbollah have risen lately, especially since one of the organization's warehouses of Katyusha rockets in southern Lebanon blew up about two weeks ago. In response, defense officials have held several high-level consultations on the situation.

The explosion revealed that Hezbollah was still stockpiling rockets south of the Litani River, in violation of Lebanon's obligations under UN Security Council Resolution 1701, which marked the end of the Second Lebanon War in 2006.

From Israel's standpoint, this revelation was advantageous: It caused the United States to convene a special Security Council session, which Hezbollah worries might influence the upcoming council debate on extending the mandate of the UN Interim Force in Lebanon. Hezbollah does not want UNIFIL to be allowed to expand its searches for arms in southern Lebanon.

Shortly after the explosion, a group of Shi'ite demonstrators staged a border provocation by crossing over into Israeli-controlled territory at Shaba Farms. Moreover, since then, Hezbollah Secretary General Hassan Nasrallah has made two aggressive statements. In one, he vowed to reopen the question of the Lebanese "prisoners" held by Israel - though the only remaining such "prisoner" is a terrorist killed in 1978 whose body was subsequently lost. In the second declaration, this weekend, he claimed that Israel plans to attack Lebanon again within the year.

The explosion was merely the latest in a series of recent setbacks suffered by the organization, most of which it blames on Israel. The most serious was the assassination of senior Hezbollah official Imad Mughniyeh in Damascus in February 2008 - which, despite numerous attempts, the group has not yet succeeded in avenging.

The movement's leaders may also feel a need to act in order to restore their deterrence against Israel - especially given the boasts of numerous Israeli officials two weeks ago, on the third anniversary of the outbreak of the Second Lebanon War, about the quiet that has reigned on the border since then.

Nevertheless, defense officials still believe the organization is more likely to try to strike Israeli targets abroad than to start trouble along the border.

Senior IDF officers believe that Hezbollah has completely rebuilt its network of bunkers and arms stockpiles in south Lebanon, but has located them almost entirely inside Shi'ite villages rather than in open areas, as it did sometimes in the past. The warehouse explosion revealed this fact, and has prompted Hezbollah to worry that Israeli intelligence may know where its new bases are located.

The organization is also under pressure due to events unrelated to Israel: It lost the recent Lebanese elections, and its patron, Iran, is now in the throes of domestic upheaval. These could serve as moderating factors, but could also spur it to engage in provocative activity.