The biennial Dubai Airshow opened on Sunday as the world's biggest defence companies promoted their weapons amid heightened tensions between Saudi Arabia and Iran.

Other airlines also are taking part, but missing from the trade show this year is one of the region's largest long-haul carriers, Qatar Airways, amid diplomatic fallout between Qatar and four Arab nations.

The airline's business has suffered under Trump's travel bans affecting predominantly Muslim nations, as well as the recent ban on laptops in airplane cabins. The air show comes as the Qatar dispute is now in its fifth month with no resolution in sight.

Qatar Airways previously had played a big role in the Dubai Airshow, reserving a large pavilion and displaying its latest aircraft to visitors. At the start of the air show, Dubai-based Emirates, the Middle East's largest carrier, unveiled new, state-of-the-art, first class private suites.

In previous years, major Mideast carriers have flexed their spending power at the Dubai Airshow, including $140 billion in new orders announced in 2013 before the collapse of oil prices.