With tensions mounting along their shared border, Israel's military says Hezbollah is moving fighters and weapons into the villages of south Lebanon, building up a secret network of arms warehouses, bunkers and command posts in preparation for war.
The Israeli military has begun releasing detailed information about what it calls Hezbollah's new border deployment, four years after a cross-border raid by its guerrillas triggered a 34-day war.
A reminder of the volatility came on August 3, when Lebanese troops fired at Israeli soldiers clearing brush on their side of the border. One Israeli officer was killed, another badly wounded, and a retaliatory helicopter strike killed two Lebanese soldiers and a reporter.
Hezbollah, which is armed by Iran and Syria and is more powerful than the Lebanese military, stayed out of the Aug. 3 fight. But its leader, Sheik Hassan Nasrallah, threatened that he would intervene next time. He has also said that if war breaks out again his forces will fire rockets into Tel Aviv.
Neither side has signaled that another war is imminent, but the Israelis' unusual openness about what they claim to know of Hezbollah's preparations seems to have two goals: to show the reach of their intelligence, and to stake their claim that if another war breaks out and many civilians die, it will be because Hezbollah placed its armaments and fighters in their midst.
Israel's military says Hezbollah has changed strategy since the last war, moving most of its fighters and weapons from wooded rural areas into villages. It says the aim is to avoid detection and use to civilians for cover if war erupts.
The military says all of this exists under the nose of 12,000 international peacekeepers who, by their own count, conduct up to 340 patrols a day in south Lebanon but are hobbled by a hostile population and rules preventing them from searching private property.
In an interview with The Associated Press on Mount Adir, a hill overlooking the border, an officer from the military's Northern Command pointed through the summer haze at the village of Aita al-Shaab.
One of its southernmost buildings, a white structure housing mentally handicapped children, is a Hezbollah lookout post, the officer said. Several guerrilla command posts are in civilian buildings in the center of Aita al-Shaab, she said, with several dozen fighters able to move among houses through underground tunnels. The military would not allow her name to be used because of the sensitivity of her job.
The village also houses a network of warehouses holding arms trucked in from Iran via Syria, she said, some in stand-alone structures and some in smaller stashes in garages, basements and buried under backyards.
The officer said the guerrillas now have 5,000 fighters operating in the buffer zone between the border and the Litani River — a strip ranging from 5 kilometers to 30 kilometers (3 miles to 18 miles) wide — which is supposed to be free of militant activity under the 2006 cease-fire. In late 2009, Nasrallah said Hezbollah's rocket arsenal stood at 30,000. Israel says it's now about 40,000.
Israel's intelligence probably comes from surveillance flights over Lebanese territory, spy satellites and Lebanese agents. But the military provides no proof of its claims, saying that could compromise its sources, and the peacekeeping force says it sees no evidence of new military infrastructure. Hezbollah officials did not respond to requests for comment on Israel's accusations.
It's difficult to independently confirm the allegations on the ground. The south Lebanese, mostly Shiite like Hezbollah, tend to support the movement and rarely criticize it publicly or volunteer information. Hezbollah members or supporters often attach themselves to journalists entering villages, shadowing them and discouraging photography.
South Lebanon is festooned with posters of the bearded, turbaned Nasrallah, but the only visible hint of Hezbollah fighters are the bearded men in civilian clothes who travel on motorbikes or in cars and occasionally approach reporters working in the area.
In July, looking to build its case that Hezbollah is digging in among civilians, the military released maps, photographs and a 3-D simulation of the streets and houses of another Lebanese town, Khiam.
The simulation shows one arms storeroom, a squat, freestanding building colored red, located 130 meters (150 yards) from a school, colored blue. A map on the military's Web site purports to pinpoint 12 arms storerooms and three command posts in the town.
The Israeli implication is clear: If another war erupts, many civilians will die.
In 2006, Israel responded to the Hezbollah border raid with a heavy bombardment of the south and then invaded, while Hezbollah fired thousands of rockets into northern Israel. The fighting killed 160 Israelis and around 1,200 Lebanese, according to official counts from each side. Israelis were dismayed to find their military suffering from organizational and supply problems, and were infuriated by international censure over the civilian death toll. That criticism was repeated even more forcefully over Israel's Gaza offensive two winters ago.
But the Lebanon border has been largely quiet since 2006. Hezbollah has not fired a rocket in the past four years — though Palestinian militant groups have — and the Israeli officer killed in early August was the military's first fatality on the frontier since 2006.
UNIFIL, the international peacekeeping force, "has not found any evidence of new military infrastructure in its area of operations," said spokesman Neeraj Singh. "Only on a few occasions, UNIFIL found armed elements in the area with personal weapons like AK-47s."
While saying UNIFIL had made "significant progress" in helping the Lebanese army secure the south, he acknowledged that the peacekeepers are barred from searching private property, where the Israelis say much of the evidence of the guerrillas' presence would be found.
Some indications of Hezbollah activity in the south have surfaced unintentionally. When a building at Khirbet Silim exploded on July 15, 2009, peacekeepers identified it as an actively maintained Hezbollah arms warehouse. Another storehouse blew up in October, the Israelis say, and in December, according to Singh, peacekeepers caught a "group of individuals" with about 250 kilograms (550 pounds) of explosives.
UNIFIL's performance has implications beyond south Lebanon. If the Israelis turn out to be right about the Hezbollah buildup, it will undermine their trust in international forces to police other volatile areas, such as Gaza and the West Bank, under a peace treaty.
In preparation for a new round against Hezbollah, the Israeli military has simulated parts of south Lebanon at a training base called Elyakim, about an hour's drive south from the border. A second facility in central Israel is nearing completion.
One day in late July, near a mock Lebanese village of gray concrete, a company of sweating Israeli infantry recruits staged a maneuver through thick Lebanese-style undergrowth, complete with rockets hidden in the bushes and bombs camouflaged as rocks.
A square metal cover on the earth opened onto a concrete tunnel where Lt. Natan Mann stood in the dark, drilling his men for the real thing.
"The army has made tactical changes and changes in its mindset," said Mann, 23, one hand on the plastic grip of his rifle. "We're either at war, or we're training for war."