Security is high around the Queen and world leaders as they attend the Commonwealth Heads of Government Meeting in Malta.
The Prime Minister and Foreign Secretary Philip Hammond are among leaders from 53 nations attending the two-day summit.
David Cameron has announced plans to set up a Commonwealth unit targeting the extremist "scourge" that is fuelling international terrorism.
He has pledged £5 million to help countries find new ways of stopping "poisonous ideologies" from taking hold.
The Queen, who is accompanied by the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall, will give a speech and host a reception for new Commonwealth leaders.
The event will feature more than 360 artists and performers, including the Maltese Philharmonic Orchestra and tenor Joseph Calleja.
The Royals will go on to tour Malta. The Queen and the Duke of Edinburgh are said to have a deep affection for the island where they lived at the start of their marriage.