The leaders of Germany and France have called for a unified approach to fostering world peace at a Paris forum attended by dozens of heads of state, with one notable exception: US President Donald Trump.
The Paris Peace Forum on Sunday followed a ceremony in the French capital to mark the centenary of the end of World War I.
German Chancellor Angela Merkel opened with a warning that "blinkered" nationalism was gaining ground in Europe and beyond.
Echoing earlier comments made by Macron, she said there was a worrying readiness by some to promote self interest and ignore ties that have underpinned peace since the end of World War II.
"Most of the challenges today cannot be solved by one nation alone, but together. That's why we need a common approach," Merkel told the audience.
"If isolation wasn't the solution 100 years ago, how can it be today in such an interconnected world?"
Leaders including Russian President Vladimir Putin and his Turkish counterpart Tayyip Erdogan were among those who listened as Merkel, Macron and United Nations Secretary General Antonio Gutteres lauded the UN and institutions like it that seek multilateral solutions to global problems.
Trump, who champions a policy of "America first" and has said he is proud to be a nationalist, snubbed the event.
Air Force One departed Paris for Washington shortly after the peace forum opened.
Earlier on Sunday, Macron led a solemn ceremony to commemorate the centenary of the Armistice that brought WWI to an end, and appeared to take aim at Trump as he warned of the perils of resurgent nationalism.
