Barring Russian President Vladimir Putin for a third time, the Group of Seven leaders invited others beyond the club of rich nations, including Iraq's premier and Nigeria's president, both battling deadly Islamist violence.
Iraq's Prime Minister Haider al-Abadi was scheduled to discuss the US-led campaign to help his country fight the Islamic State extremists who launched a lightning offensive a year ago and have snatched over a third of the country's territory.
The power summit, held in a tightly-secured resort in the picture-postcard Bavarian Alps, was also expected to hold talks on "foreign fighters" and the threat Islamist extremism poses to their countries -- Britain, Canada, France, Germany, Italy, Japan and the United States.
Another visitor to the summit, Nigeria's newly elected President Muhammadu Buhari, was to put a "shopping list" to the G7 leaders, seeking help to fight an insurgency by Boko Haram Islamists blamed for 15,000 deaths since 2009.
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The first day of the G7 was dominated by the Ukraine conflict, as Obama and the summit host, Chancellor Angela Merkel, urged the global community to stand firm against Moscow until it complies with a Ukraine ceasefire deal struck in the Belarussian capital Minsk.
"I expect that we should send a firm signal here. Not sanctions as an end to itself, but sanctions... To reach a target," Merkel told ZDF television.
Japan's Prime Minister Shinzo Abe and Canada's Stephen Harper on Saturday made a point of visiting Kiev on their way to the summit, to voice support for Ukraine's embattled leaders, as a recent flare-up in fighting in the east has left at least 28 dead.