The Queen is preparing to host US President Donald Trump at a Buckingham Palace reception for Nato leaders.
Mr Trump landed at Stansted Airport in Air Force One with his wife Melania at 10pm on Monday for his third visit as US President.
He will gather with Western politicians and their partners in the royal residence’s grand State Rooms.
The Queen, the Prince of Wales and the Duchess of Cornwall will formally greet the Nato leaders at the reception, which marks 70 years of the alliance.
Charles and the monarch will then join the politicians for a group photograph.
The royals will be out in force for the event, including the Duchess of Cambridge, the Earl of Wessex, the Princess Royal, the Duke and Duchess of Gloucester and Princess Alexandra.
The Duke of Cambridge is away in the Middle East and the Duke and Duchess of Sussex are on a six-week break from royal engagements.
The Duke of York, who stepped down from public duties after his disastrous Newsnight interview about his association with convicted paedophile Jeffrey Epstein, is not attending.
Mr Trump has repeatedly criticised Nato, describing it as “obsolete and disproportionately too expensive (and unfair) for the US”.
Nato – the North Atlantic Treaty Organisation – was established in Washington on April 4 1949.
It began as a 12-member alliance to counterbalance the growing military might of the Soviet Union and to keep the peace in post-war Europe.
The political and military alliance now has 29 member countries.