Senior Israeli commanders sat on a hilltop here this week and watched their troops attack Hezbollah operatives in a southern Lebanese village.

Except that it wasn’t a real village — it was a mock-up, a Hollywood-style stage set, built at this base in northern Israel to mimic the kind of town the Israeli army would target in the event of war. And the “Hezbollah” fighters? They were Israelis, too, soldiers acting the part of the enemy. The guns fired blanks, the grenades were just smoke bombs and nobody died.

But the intent was deadly serious.

The Israel Defense Forces are currently reviewing and refining their tactics for potential house-to-house fighting in Lebanon and Syria.

Israeli military officers have said in interviews that, although they believe an imminent assault from the north is unlikely, the chance of accidental spillover from the civil war in Syria is high.

According to estimates by Israeli military intelligence, 2,000 to 4,000 members of the military wing of Lebanon’s Shiite organization Hezbollah — 10 to 15 percent of the group’s total fighters — are gaining valuable battlefield experience fighting Syria’s rebels on behalf of Syrian President Bashar al-Assad.

What concerns Israel most, though, said a top Israeli officer who spoke with foreign reporters on the condition of anonymity, is what he called “the slippery slope.”

“Syria gives sophisticated weapons to Hezbollah. Hezbollah tries to smuggle weapons into Lebanon. We try to stop it. They respond,” he said. “It could happen tomorrow.”

Israeli commanders say there are 50,000 to 100,000 short- and medium-range rockets, new and old, in 200 villages in southern Lebanon that are controlled by Hezbollah, whose military wing was designated a terrorist organization by the European Union in July.

If those rockets are launched, “we will have to go into the villages and find them,” the military officer said. “You cannot win this without boots on the ground.”

“It will cause a lot of damage to those villages,” he said.

In the 2006 war between Israel and Hezbollah, fighting raged for 34 days. More than 1,000 Lebanese were killed; 165 Israelis died.

Israeli military officials said that during one week of fighting in November, the Palestinian political and militant group Hamas, which controls the Gaza Strip, and its brigades fired 1,500 rockets at Israel. Hezbollah, they said, could launch 1,500 a day — for a month or more — if the group went all out.

The Israelis say that the Hezbollah rockets are located in garages, basements, barns, bedrooms and tunnels and that the militant group has been deploying hydraulic systems to enable it to fire rockets from upper-story windows.

“So we have a problem,” said Archie Leonard, a second lieutenant at the training school here. “You would want to attack a village with as much force as possible. But we can’t, because it is filled with civilians.”

Leonard said standard procedure would be for the Israeli air force to drop pamphlets alerting a village that Israeli troops were on the way. Those tactics were used recently in Gaza. Sometimes residents fled, and sometimes they didn’t.

The mock village at the Elyakim base consists of dozens of gray structures, with larger buildings along a main road, a more densely populated section that the Israeli troops call “the casbah” and scattered homes with gardens.

All morning on a recent day, squads of soldiers drilled in the empty ersatz village — on how to turn a corner, watch for snipers, clear a room. One trainer compared the training to learning dance steps.

“A village is an incredibly dangerous environment,” said Sgt. Jeffrey Yeger, a tank commander. The streets are narrow. Tanks can get stuck, their turrets unable to spin. And the rooftops are deadly launching platforms for shoulder-fired antitank missiles.

These days, the Israeli troops are focusing more on tunnel warfare, because their intelligence suggests that Hezbollah has dug extensive, sophisticated underground networks in and around villages, complete with cameras, Internet connections and booby traps.

In one drill, a platoon worked its way through brush, finding tunnel entrances and leaving a few men at each opening to prevent an ambush.

The troops seemed competent, but they made mistakes. Their rifle straps caught on the rungs of ladders leading into tunnels. Their ropes got tangled, and sometimes they hesitated when they were supposed to move and moved when their instructor wanted them to wait.

“It is going well. They know the basics, and now we need to focus on the details,” said trainer Sagiv Kehlia, a second lieutenant.

“They will win the next war, I’m sure of it,” he said.

The troops took the exercise seriously, although a couple of soldiers flashed peace or victory signs at the photographers and reporters on hand to watch.

When they practiced confronting a Hezbollah opponent at the end of a tunnel, the Israeli soldiers threw rocks to simulate stun grenades, then rushed in yelling, “Fire, fire, fire!”

Then they shouted, “The terrorist is dead!”

And then they practiced again.