The biennial Defence and Security Equipment International at the ExCel Centre has attracted hundreds of companies, ranging from the world's biggest producers of warplanes and missiles to niche hi-tech firms, although exhibitors also include makers of life-saving and medical products.
Delegations from 65 governments have been invited, including Bahrain, a longtime recipient of British arms, whose security forces have recently fired at unarmed demonstrators. Other invited Middle East governments include Iraq, Oman, Qatar, and Saudi Arabia.
India, which may soon overtake Saudi Arabia as Britain's largest single arms market, is on the guest list, which also features Algeria and Morocco.
Libya, whose arms dealers were guests two years ago, has not been invited, although it can expect to be asked next time when its new government should be in power. China, invited two years ago, is not on the official guestlist this time.
The Campaign Against the Arms Trade (CAAT) and other groups are planning a mass lobby of parliament and demonstrations in the Docklands.