Leaders from the group of leading industrial nations, the G7, have just finished a meeting in Sicily.
The G7 consists of Canada, France, Germany, Italy, Japan, the UK and the US, while the EU also has representatives present.
The group failed to agree on climate change.
US President Donald Trump, attending his first such summit, held off from endorsing the 2015 deal on reducing greenhouse gas emissions.
German Chancellor Angela Merkel said the discussions with Mr Trump had been “intensive”.
“The United States made clear that it has not yet made its decision and will not do so here, but rather will continue to work on this,” she said.
President Trump, who once dismissed global warming as a “hoax”, has previously threatened to pull out of the Paris agreement.
However, the leaders ‘united’ in fight against terrorism
The leaders signed a document saying more should be done by internet companies to identify and remove extremist material.