A US Air Force A-10 Thunderbolt attack aircraft and a C-130 Super Hercules transport were on the tarmac at Hanoi's Gia Lam military airfield for the event.

Thousands of people attended including hundreds of uniformed Vietnamese soldiers, some of whom posed for selfies with US troops ahead of next year's 50th anniversary of the end of the Vietnam War.

The defence expo featured Chinese firms for the first time, including major state-owned defence conglomerate Norinco, or China North Industries Corporation.

Successive Vietnamese governments have been heavily reliant on arms supplied by Russia for decades.

The country accounted for more than 80 percent of Vietnam's arms imports between 1995 and 2023, according to data from the Stockholm International Peace Research Institute (SIPRI).

But imports from Russia have dropped off in recent years amid international sanctions over its invasion of Ukraine.

"The war in Ukraine has exposed the vulnerabilities of relying too heavily on Russian arms," said Nguyen Khac Giang, a visiting fellow at the ISEAS-Yusof Ishak Institute in Singapore.

"Diversification isn't just a necessity, it's an opportunity for Vietnam to upgrade to more advanced systems while reducing dependence on any single partner," Giang said.

"The expo is Vietnam's way of signalling it's open to new partnerships."

Boeing and Lockheed Martin were among 14 American companies at the fair, while two exhibitors were Chinese and others were from Germany, Iran, Israel and Ukraine, as well as Russia.

As well as aircraft, they put on display tanks, missiles, drones, firearms and radar systems, including by several Vietnamese firms.

Speaking on the sidelines of the fair, US Ambassador to Vietnam Marc Knapper said US and Vietnamese companies could potentially work together in areas such as joint production and technology transfers.

"Our goal is to ensure that Vietnam has what it needs to defend its interests, at sea, in the air, on the ground and in cyberspace," he said.

Both Washington and Hanoi share concerns about Beijing's moves to assert its presence in the contested South China Sea, where Vietnam and other Southeast Asian nations have competing claims with China.

At the opening ceremony, Vietnamese Prime Minister Pham Minh Chinh described the expo as "delivering a message of peace, cooperation, and shared development".

lam-aph/sco

BOEING

LOCKHEED MARTIN

Airbus Group