Daniel Nisman and Avi Nave write: Last week Iran sent a high-level envoy, Saeed Jalili, on a particularly controversial public-relations tour to Lebanon and Syria, the most explosive corner of the region. After ruffling feathers during a Beirut stopover, Mr. Jalili traveled to Damascus to meet with President Bashar al- Assad, where he declared the ties between Iran, Syria, and Hezbollah to be an “axis of resistance.”

Jalili is an iconic figure, whose position as the head of Iran’s Supreme National Security Council also affords him the role of chief negotiator for Iran’s contentious nuclear program. Amidst a deadlock in negotiations and a rehashing of threatening rhetoric, Jalili’s visit was meant to remind the Israelis that Iran’s proxies on Israel’s northern doorstep remain ready and willing to plunge the region into chaos if Israel strikes Iran’s nuclear facilities.

It appears however, that Iran’s allies in the eastern Mediterranean may not be as keen about going to war for the ayatollahs as Tehran would like – and the Israelis know it.

The threat of a simultaneous war with Hezbollah, Syria, and Gaza militants is the primary concern for the Israeli security establishment as it weighs a strike on Iran. Dubbed “the long arm of Iran” at the Israel Defense ForcesI headquarters, Hezbollah in Lebanon is said to possess more than 70,000 missiles that can strike as far south as Israel’s nuclear reactor near the city of Dimona – nearly 140 miles from the Lebanese border.

Combine this arsenal with the more than 10,000 rockets and missiles in the Gaza Strip and with Mr. Assad’s chemical weapons, and the threat to Israel’s home front is the most formidable since the 1973 Yom Kippur War when Egypt and Syria attacked Israel.

And yet, Israeli leaders seem content to shrug off this threat. On two recent occasions, Defense Minister Ehud Barak boldly estimated that Israel would sustain 300 to 500 casualties in a conflict with Iran and its proxies. Such an estimate suggests that Mr. Barak himself does not believe that Israeli cities will bear the full brunt of Iran’s “long arm” as a consequence to a strike.

Prime Minister Benjamin Netanyahu also dismissed the danger of regional conflict by stating that these threats to the home front are “dwarfed” by a nuclear Iran.

Judging from their statements, Hezbollah leaders aren’t so sure they want to enter into a conflict with Israel at Iran’s behest. In February 2012, Hezbollah leader Hassan Nasrallah said, “I tell you that the Iranian leadership will not ask Hezbollah to do anything. On that day, we will sit, think and decide what we will do.”

Mr. Nasrallah’s hesitation is understandable. Entering into broad conflict with Israel would result in even greater destruction to Lebanon than in the 2006 Lebanon war. This time, Hezbollah would be unable to replenish its stockpiles or rebuild destroyed villages so easily. Nasrallah’s guarantor in Damascus is on his last legs, while his primary bankrollers in Tehran have already cut funding to the group as a result of sanctions and diversion of resources to Syria.

Note that when Nasrallah issued a warning to Israel on Friday he described the devastating response Hezbollah would launch in response to an attack on Lebanon.

Speaking about Israel’s repeated threats to attack Iran’s nuclear facilities, Nasrallah said the Jewish state knows very well that Iran’s response would be devastating.

“Iran is a strong and courageous state … The Israelis, myself and everyone else know that Iran’s response would be great and shocking were it to be hit by Israel,” he said.

“If Israel attacked, it would give Iran the golden opportunity it has been waiting for,” Nasrallah added.

He added that Israel was afraid of Iran and that the former recognized that the cost of a strike on the Islamic Republic outweighs the benefits.

Reading between the lines, the Hezbollah leader seems to be indicating that like their counterparts in Gaza, Lebanon’s resistance fighters have the same preeminent concern: self defense. They are not mere proxies for Tehran and will ultimately act in whatever they perceive to be their own interests.