The G7 summit will host world leaders as they meet to discuss climate change, trade, migration and ties with Africa.
The Manchester bombing and conflicts in North Korea and Syria are also certain to crop up during the two-day meeting between the world’s seven major economies.
Donald Trump will likely use the summit to push NATO allies to “contribute their fair share”, after he berated leaders yesterday for their alleged shortcomings.
Theresa May will call on leaders to do more to pressure technology companies into blocking extremist content online, and will argue that the fight against ISIS is moving from the “battlefield to the internet”.
As the G7 summit gets underway, here are live updates and the latest news from Sicily.
Friday May 26
3.00pm: US President Donald Trump said that North Korea was a "big problem", but assured Japanese Prime Minister Shinzo Abe that issues surrounding the secretive Asian state would be resolved.
He said: "It is very much on our minds… It's a big problem, it's a world problem and it will be solved. At some point it will be solved. You can bet on that," Trump said sitting alongside Abe in a bilateral meeting ahead of a Group of Seven summit."
"President Trump and Prime Minister Abe agreed their teams would cooperate to enhance sanctions on North Korea, including by identifying and sanctioning entities that support North Korea's ballistic missile and nuclear programs," the White House said after the two men held a one-on-one meeting in Sicily.
"They also agreed to further strengthen the alliance between the United States and Japan, to further each country's capability to deter and defend against threats from North Korea," the statement said.
North Korea's growing nuclear and missile threat is seen as a major security challenge for Trump and Abe both. Trump has vowed to prevent the country from being able to hit the United States with a nuclear missile, a capability experts say Pyongyang could have some time after 2020.
2.40pm: The summit has kicked off with a ceremony at an ancient Greek theatre, overlooking the sea. Leaders are then attending a meeting on terrorism and climate change. European leaders have signalled they will push Trump on Paris emissions deal.
G7 leaders around the table at the summit
2.20pm: The G7 leaders have been pictured arriving at the summit in Sicily as talks begin.
Donald Tusk, European Council president, said before the meeting: “No doubt, this will be the most challenging G7 summit in years,” due to the leaders' differing positions on climate change and trade.
He added that Donald Trump agrees that Brexit is “just an incident, not a trend”.
“I was positively surprised by President Trump’s comments on Brexit because it was clear for both of us that in fact the EU27 is more united after Brexit than before,” Mr Tusk said, before moving the topic of conversation to terror.
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He said that he was in agreement with Mr Trump that a “tough, even brutal” approach was necessary to combat ISIS.
“It is understandable that terrorism, counter-terrorism, ISIS were one of the main topics during our meeting with President Trump. Manchester was the most tragic context of our discussions,” he said.
2.00pm: European Commission president Jean Claude Juncker took a swipe at Donald Trump this morning. He told reporters: There a four new leaders around the table. We are veterans but it will be very interesting to know thesew new colleagues in a better way. We uphold freedom, democracy and the rule of law.
"Those in Europe and elsewhere who do not see how globalisation works for them. We must build bridges not walls."
G7 summit: Donald Trump, Theresa May, Angela Merkel and Emmanuel Macron are among those present
G7 summit: Donald Trump yesterday attacked his European Nato allies
When asked about Theresa May’s claim that the EU could be forced to pay money to the UK as part of Brexit negotiations, Mr Tusk said: “No, we have to respect our obligations and I think it’s not about money, it’s about rules and also it’s about a good basis for our future relations.
“This is why we will be very consistent in this problem, but please believe me, it’s not because of money but because of rules.”
Theresa May started her say with a meeting with Emmanuel Macron, where the pair agreed on the need to stop the “spread of poisonous material and propaganda on the internet that is leading people down the path towards terrorism”.
Mrs May thanks Mr Macron for his solidarity in the aftermath of the Manchester bombing, which she called “one of our worst terrorist incidents that we’ve ever experienced”.
“France itself knows what it is like to suffer from terrorist attacks. And these incidents show us why it is so important for us to work together in defeating terrorism,” she added.
NATO countries' heads of states gather in Brussels
Thu, May 25, 2017
NATO countries' heads of states and governments gather in Brussels for a one-day meeting
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U.S. President Donald Trump and Britain's Prime Minister Theresa May react during a ceremony at the new NATO headquarters in Brussels
G7 summit: Jean Claude Juncker speaking ahead of G7 summit of leaders
Mr Macron offered his support, saying: “We will be here to cooperate and do everything we can in order to increase this cooperation at the European level, in order to do more from a bilateral point of view against terrorism.”
Later today, the G7 leaders will discuss Africa’s economic and migration issues.
Italy has chosen to host the G7 summit in Sicily to draw attention to the continent, which is 140 miles from the island.
“Africa is very important for us. Indeed, it is perhaps the focus of our G7 presidency," said Raffaele Trombetta, the senior Italian diplomat who has led behind-the-scenes negotiations on the G7 agenda with colleagues from the United States, Japan, Germany, Britain, France and Canada.
“We don't just want to talk about crises, like migration and famine, but also to promote innovation in Africa and see what we can do to help," he told Reuters.