Syria will be one of the main topics at next week's G8 meeting, being held in Northern Ireland.
The town of Enniskillen, with a population of 15,000, will also become the temporary home to nearly 9,000 police officers, to protect leaders of the eight big industrial countries.
ITV News Correspondent Martin Geissler reports on the security operation:
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Temperatures will reach around 28 Celsius (82F) at their highest.
A minute's silence will be observed at 11am on Thursday in remembrance of those who lost their lives in the Manchester Arena attack.
New research has found those who consumed two cups had a 35% reduced risk, and for those who drank five cups, the risk halved.