A biennial defense exhibition kicked off in Seongnam, south of Seoul, on Tuesday, offering an in-depth look at state-of-the-art military hardware like stealth jets, advanced missile interceptors and hydrogen-powered drones.

The five-day Seoul International Aerospace & Defense Exhibition (ADEX) at Seoul Air Base comes amid lingering regional tensions from North Korea's evolving threats and an intensifying Sino-US rivalry.

This year's edition is expected to provide a rare chance for defense companies at home and abroad to take stock of progress in the arms industry and explore business opportunities, as the COVID-19 pandemic has impeded their in-person exchanges.

The 2021 exhibition involves 440 companies from 28 countries, including 171 from overseas, the organizers said. It marks the largest number of participating firms since the exhibition was launched in 1996.

Among the items on display are large hydrogen-fuel drones, virtual reality-based training systems, laser weapons systems and multipurpose unmanned vehicles, as well as dozens of military aircraft, such as FA-50 fighters and KT-1 basic trainer jets.

The radar-evading F-35A, manufactured by Lockheed Martin Corp., is unveiled to the general public for the first time since the warplane was first delivered to an Air Force unit in South Korea in 2019. During the 2019 exhibition, a mock-up of the stealth fighter was on display.

General Atomics Aeronautical Systems Inc. presented the MQ-1C Gray Eagle combat drone. Capable of high-definition surveillance, the drone is known to carry four air-to-ground anti-armor missiles.

The ADEX features ground-based arms as well, including the K-2 battle tanks and K-9 howitzer.

The ADEX showcases a wide array of hardware that can be applied to other areas, including space development and urban air mobility, as well.

Hanwha Aerospace Co. displayed a real 75-ton thrust engine, which is the same model installed in the country's homegrown space rocket, the Nuri, which will be launched Thursday at the Naro Space Center in Goheung, 473 kilometers south of Seoul.

LIG Nex1 Co. unveiled the hydrogen-powered cargo drone, currently being developed to carry 200 kilograms of freight, for release by 2025.

Around 20 international symposiums and conferences will be held on the sidelines of the exhibition as well, organizers added. (Yonhap)