Lebanese and American officials gathered Wednesday to mark the delivery of more than 200 anti-tank missiles the United States says will help Lebanon's army defend its borders against terrorists.

The 200 US-made TOW-II missiles and launchers, valued more than $10 million, were delivered in late May as part of a joint US-Saudi effort to support Lebanon's army, said US ambassador to Lebanon David Hale.

"We are absolutely committed to making sure that the army has the capacity to be the sole defender of Lebanese territory and its borders, and is answerable to the state and to the Lebanese people through the state," he said.

Lebanese soldiers fired artillery, drove through the hills of the Bekaa Valley, and flew over the area in helicopters.

The four-year civil war in neighbouring Syria has seen violence spill over into Lebanon.

Jihadist fighters, including Al-Qaeda's Syria affiliate and the extremist Islamic State group, have sought refuge in the rocky terrain on the Syrian-Lebanese border.

In August last year, Lebanese security forces clashed with these groups when they briefly overran the border town of Arsal.

Since then, the US has provided Lebanon's armed forces with $82.5 million in weapons and ammunition, according to the US embassy.

"This is a long term commitment, and we will stand by Lebanon's side in this regard until these terrorists are defeated," Hale said.

The US-made TOW-IIs are the same kind delivered by Western backers to Syrian rebels in April 2014.

The new delivery comes in addition to artillery and ammunition that the US provided to Lebanon in February.

A $3 billion Saudi-funded programme also brought French-made anti-tank guided missiles to Lebanon in April, to be followed over the next four years by combat and transport vehicles, three small warships, and a range of surveillance and communications.