The US ambassador to Lebanon said on Sunday that $25m worth of weapons and ammunition had arrived in Beirut, the latest American assistance to Lebanon’s army as it fights Islamic extremists along the border with Syria.

Ambassador David Hale said the equipment includes more than 70 M198 howitzers and more than 26m rounds of ammunition and artillery “of all shapes and sizes, including heavy artillery”.

Extremists have launched several attacks on Lebanese troops over the past months in areas near the Syrian border, killing and wounding scores of troops. The most serious attack occurred in August, when members of the al-Qaida-linked Nusra Front and the Islamic State (Isis) group captured two dozen Lebanese soldiers. They have killed four of them and still hold the rest.

Lebanese and American officials attended a handover ceremony on Sunday at Beirut’s port.

“We are very proud of this and this is top-of-the-line equipment. This is the best that there is in the marketplace. It’s what our soldiers use,” Hale said. “I know that in a matter of days it’s going to be what your brave soldiers are using in the battle to defeat terrorism and extremism that is pouring across the border from Syria.”

Hale told reporters Lebanon has become the fifth-largest recipient of US foreign military assistance. He added that weapons worth more than $100m were given to Lebanon last year and more than a $1bn in the last eight years.

He said the US help to Lebanon will continue “until the job is done”.

The Lebanese military is generally seen as a unifying force, and draws its ranks from all of the country’s sects – Sunni and Shia Muslim, Christian and Druze. But the armed forces have struggled to contain the escalating violence in the country.

This is the latest aid promised to Lebanon. In November, France and Saudi Arabia signed an agreement for Paris to provide the Lebanese army with $3bn worth of weapons paid for by Riyadh. The first shipment of those weapons is expected to arrive in April.