The Group of 20 summit is set to open in Johannesburg on Saturday amid the absence of several major world leaders, including the presidents of the United States, Russia and China, raising expectations of tough discussions over Washington’s proposed peace plan for Ukraine.

South African President Cyril Ramaphosa, the summit host, said the meeting — the first G20 gathering to be held on the African continent — will focus on global solidarity, equality and sustainable development.

U.S. President Donald Trump, Russia’s Vladimir Putin and China’s Xi Jinping are among the leaders who cancelled their attendance. The presidents of Argentina and Mexico will also be absent.

The summit is expected to tackle debt relief for emerging and developing economies, a just transition in the energy sector, fair and clean use of critical minerals, climate-related burden-sharing and global food security.

United Nations Secretary-General António Guterres on Friday urged G20 members to “use their influence and their voices to help end conflicts around the world.”