Lebanon criticized on Tuesday the U.S. decision to suspend $100 million of military aid over concerns that Iranian—backed Hezbollah may have influence over the Arab country’s army and American—supplied weapons could be used to threaten neighbouring Israel.

The cutoff renewed focus on the unusual power dynamics in Lebanon, where Hezbollah’s militia is the country’s most powerful military force, with an arsenal that far outweighs that of the Western—backed national army. The power balance has long worried the U.S. and close ally Israel, which is Hezbollah’s sworn enemy.

The chairman of the U.S. House Foreign Affairs Committee, Rep. Howard Berman, said on Monday he suspended the assistance to the Lebanese Armed Forces on August 2. He said a deadly gun-battle between Israeli and Lebanese forces along their border last week, a day after the aid was suspended, reinforced his decision.

Though Lebanese officials and Hezbollah insisted the Shiite militant group was not involved, some critics in Israel and the U.S. are charging that Hezbollah may have infiltrated the army.

The Lebanese government said the cutoff was “unwarranted” and hurt American—backed efforts to build up its national army. For years, the U.S. has pumped money into Lebanon’s military, hoping a strengthened army would extend state authority across the country and sideline Hezbollah.

“The last thing that the U.S. or any other friend of Lebanon should do is to weaken the effort to build up our national army,” Mohamed Chatah, an adviser to Prime Minister Saad Hariri, told The Associated Press.

He added that government officials were contacting Washington “to make sure that there is a better and fuller understanding of the situation in Lebanon and along the border.”

On the same day Congress announced its suspension in aid, U.S. State Department spokesman P.J. Crowley defended the assistance.

“We have an extensive military cooperation program with Lebanon because it’s in our interest to have that program,” he said. “It allows the government of Lebanon to expand its sovereignty. We believe that is in the interest of both of our countries and regional stability as a whole.”

Mr. Crowley said he was not aware of plans to re-evaluate U.S. military cooperation with Lebanon. However it is not unusual for members of Congress and the administration to differ on foreign policy issues.

Berman, a Democrat from California, said the border clash had heightened his concerns about the aid.

“Until we know more about this incident and the nature of Hezbollah influence on the (Lebanese army) and can assure that the (Lebanese army) is a responsible actor, I cannot in good conscience allow the United States to continue sending weapons to Lebanon,” he said on Monday.

The August 3 clash killed two Lebanese soldiers, a Lebanese journalist and an Israeli officer. The State Department said there was no evidence American—supplied equipment had been used by Lebanese soldiers, and that it was not yet clear whether the soldiers involved had received U.S. military training.

The clashes began after an Israeli soldier tried to remove a tree along the border, something the military has done in the past to improve its sightlines into Lebanon. Both sides claimed the tree was in their territory; the United Nations later determined it was on the Israeli side. But the clash highlighted the tensions in the area, where Israeli and Lebanese soldiers patrol within shouting distance of each other.

The fighting was the worst since 2006 in the area, underlining how easily tensions can re—ignite along the frontier where Israel and Hezbollah fought a war four years ago.

Since that war, Hezbollah has gained significant political power in Lebanon.

Lebanon’s government is now an uneasy coalition of a Western—backed bloc, headed by Hariri, and Hezbollah, which in just a few years has gained so much political power it now has a virtual veto over government decisions. Hariri’s bloc wants Hezbollah to disarm, but does not have the power to force its will.

There has long been debate over Hezbollah’s substantial arsenal.

Since Israel withdrew from south Lebanon in 2000, removing the main motive for Hezbollah’s armed struggle against the Jewish state, Hezbollah’s opponents in Lebanon have grown bolder in demanding it relinquish its weapons and in criticizing it as a rogue element.

Israel occupied south Lebanon for nearly two decades following an invasion in 1982 to fight Palestinian forces entrenched in the area.

In 2000, the army deployed in southern Lebanon, Hezbollah’s heartland, for the first time in decades. Israel, which had for years been calling for an army presence in the south, was largely supportive because it would prefer to have the Lebanese army and not Hezbollah in charge of the south.

For years, Lebanon’s 60,000—strong military was dismissed as little more than an internal security force. It has mostly stayed out of battles between Israeli forces and Hezbollah, including the 2006 war when Israeli airplanes pounded army positions while the military stayed largely on the sidelines.

Both the Bush and Obama administrations have backed sending aid to Lebanon’s army, maintaining that a professional military is critical for the government to exert its sovereign authority, which has been challenged by armed Hezbollah militants in the past.

Since it was founded at the height of Lebanon’s civil war, Hezbollah has grown into one of the most robust, organized and sophisticated resistance groups in the world with a small army of about 6,000 fighters. With an annual budget of more than $100 million largely supplied by Iran, it also runs a network of schools, charities and clinics, and has its own satellite television and radio stations.

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